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Aug. 28, 2026

Transforming the US Army Reserve for Protracted War

Joshua Yarbrough

ABSTRACT: This article argues the US Army Reserve must be transformed from an operational to an adaptive reserve to meet the demands of protracted, high-intensity warfare. The author’s analysis focuses on how the Army Reserve’s current structure lacks the strategic depth, mobilization capacity, and training to sustain long-term conflict. Drawing on historical cases, contemporary conflicts, and official documents, this article blends strategic analysis with policy recommendations, offering practitioners actionable reforms relevant to the Army Transformation Initiative and future Joint Force readiness in large-scale combat operations.

Keywords: Army Transformation Initiative, reserve component, strategic depth, protracted war, mobilization

 

“Our nation needs us ready to fight today’s battles but also to prepare for tomorrow’s wars. We must prepare by modernizing and aggressively leading with new concepts and approaches.”

—Charles Q. Brown Jr., “Message to the Joint Force”1

The United States stands at an inflection point for the national defense strategy. The global security environment is transitioning toward an era defined by strategic competition with the People’s Republic of China, where the specter of a protracted, high-intensity conflict looms larger than ever in recent history. Unlike the asymmetric wars of the past two decades, a large-scale combat operation (LSCO) against a technologically advanced peer would test the US military in ways not seen since the Cold War. Such a conflict would demand sustained, multidomain operations requiring, at a minimum, partial mobilization, which alone would exhaust the current force and leave little residual capacity for full mobilization. But the US defense strategy has prioritized cost savings and force reductions—even while engaging in low-intensity conflicts over the past 20 years.2

Fighting in permissive environments with predictable force rotations shaped decisions about the US Army’s force structure, leading to a modularized structure reliant on operationalized reserve forces. These decisions fully embraced the total Army policy first espoused in the total force policy, or Abrams Doctrine, where all Army components are required for war. To ensure the force was ready to fight rapidly, the Abrams Doctrine also emphasized not creating a hollow force where mismatches between Army manning and authorizations would leave understaffed or unfilled units unable to perform their missions. Streamlining the Army’s structure meant preserving combat arms units in the Army and Army National Guard and shifting the bulk of LSCO enablers into the US Army Reserve (Army Reserve). These decisions created an army capable of sustaining rotational requirements. Still, these decisions raise the question of whether the Army retains the endurance, resilience, and strategic depth necessary to fight with a peer adversary without rebalancing Army components.3

The Army Reserve transformed over 30 years from its historical role as a strategic reserve that augmented the Army during LSCO, to a pivotal provider of enabling capabilities for steady-state, Joint operations (table 1). Major changes included divesting almost all reserve combat arms capabilities, reducing the force-generation structure, and transitioning primarily to combat support (CS) and combat service support (CSS) units. These shifts made the Army dependent on the Army Reserve to complete every formation for routine missions and episodic surges—from the tactical to the theater level. This reliance reflects defense planning guidance and apportionment tables that instruct the Army to prepare for known, current operations and directed-contingency demands. But planning multiple contingencies against the same forces highlights how fighting even one conflict and deterring another will likely mandate full mobilization, limiting the amount of residual reserve capacity. The change to an operational reserve and the prospect of full mobilization for future conflicts underscore the need to reexamine the Army’s force structure and readiness for protracted war as part of the Army Transformation Initiative.4

Table 1. Example of active component and reserve component force-mix changes
(Source: Andrew Feickert and Lawrence Kapp, Army Active Component (AC)/Reserve Component (RC) Force Mix: Considerations and Options for Congress, Congressional Research Service (CRS) Report R43808 (CRS, 2014), 7–8. Overall decreasing force structure following the Cold War coincides with an increasing reliance on the reserve components. But the cuts have remained proportional meaning that even as the AC declines, RC structure has not increased.)
Year Active Component Levels Reserve Component Levels Active Component Percent of Force Mix Reserve Component Percent of Force Mix Total Size of Army
1989 (end of the Cold War) 770,000 776,000 49.1 50.1 1,546,000
September 11, 2001 480,000 555,000 46.4 53.6 1,035,000
2010 (peak Army strength related to war in Iraq and Afghanistan) 570,000 564,000 50.3 49.7 1,134,000
FY 2015 budget request 490,000 552,000 47.0 53.0 1,042,000
Army proposal for FY 2017 (smallest acceptable forces) 450,000 530,000 45.9 54.1 980,000
Army proposal for FY 2019 (worst case scenario) 420,000 500,000 45.6 54.4 920,000

These points raise a central question: Do the Army Reserve’s current structure and roles provide the Army with sufficient strategic depth to engage in protracted war? If not, how must the Army Reserve adapt? Whereas this question is straightforward, it belies the issue’s complexity, and seeking an answer requires dissecting the problem. First, prolonged war remains nascent and, to understand its implications for the Army, the term must be defined. Second, understanding protracted war’s broader impact on the Army enables a narrow assessment of the Army Reserve’s current capabilities and an assessment of critical shortfalls in readiness, force structure, and mobilization processes for sustained, high-intensity conflict. Third, the demands of prolonged war and its attendant shortfalls provide a lens through which to develop recommendations to modernize the Army Reserve. Finally, implementing such recommendations entails challenges and risks that must be addressed to ensure the Army Reserve remains relevant and combat-ready to support the Joint Force in an increasingly contested world.

On Protracted War and Its Implications for the US Army

Protracted War

Protracted war is not new, but this concept’s relevance has grown in modern great-power competition. Historically associated with Mao Zedong’s theory of a protracted people’s war, as well as guerrilla campaigns like the Afghanistan War, today’s protracted conflicts take on new dimensions—sustained, high-intensity combat operations against peer or near-peer adversaries. Yet, unlike Mao’s model, the pre–World War I German General Staff planning efforts—which emphasized precise mobilization timelines, contingency planning, theater logistics, reserve structures, and whole-of-society mobilization—may be a fitting historical parallel to modern, protracted conflict. Unlike the decisive campaigns envisioned in traditional doctrine, a protracted war can extend over years, leading to resource scarcity and dynamic environments that require continuous adaptation. These conflicts are not merely prolonged battles but complex engagements that alternate between intense offensive, defensive, and stability phases—often occurring simultaneously across multiple theaters.5

In protracted war, operational requirements quickly outstrip available forces, requiring full mobilization and the expansion of force-generation capacity to replace the anticipated 3,600 daily casualties. This reality is particularly challenging for the Army, given it narrowly avoided breaking the force over the past two decades by operationalizing reserve components. Force-structure reductions and persistent personnel shortages created a dependency on reserve units to ensure a sufficient deployment-to-dwell ratio for units in the active component. Yet the Army’s Regionally Aligned Readiness and Modernization Model, a force-generation model, was designed to balance operational requirements against long-term readiness, modernization, and force-structure considerations—not generate forces for high-intensity conflicts spanning large time horizons.6

Protracted war will deplete personnel, equipment, and supplies at accelerated rates—straining personnel, readiness, supply, and training capacities. High demand will exacerbate wear and tear on vehicles, weapons systems, and other equipment, leading to increased maintenance requirements and shortened life cycles. Accelerated equipment degradation can stretch supply chains and maintenance capabilities, potentially impacting operational effectiveness. Varying levels of intensity and demands across multiple theaters can further compound these issues by requiring units to maintain proficiency in a wider array of combat and stability skills. These challenges will require Army leaders to debate frontline reconstitution, unit rotations for regeneration, and force expansion, including pulling experienced personnel to create new units. Unless the Army adapts its readiness, force structure, and force-generation capabilities, the Army risks entering a prolonged conflict without the resilience needed to sustain the fight.7

Historical and Contemporary Vignettes

Historically, the Army has evolved its processes and policies for force generation and readiness (figure 1). Lessons from the Korean War and the Russia-Ukraine War help explain the difficult decisions Army leaders face when determining how to transform the force to meet the demands of protracted war. The Korean War exposed significant vulnerabilities in the US Army’s readiness and mobilization capabilities, resulting in unprepared units lacking sufficient training, modern equipment, and personnel. High attrition rates and the loss of experienced personnel severely reduced combat effectiveness, especially as the replacement operations struggled to provide ready soldiers. The war also revealed critical weaknesses in mobilization planning, with prewar assumptions allowing the US Army to mobilize large portions of the unprepared reserve component and increasing its reliance on conscription. Both outcomes hindered the Army’s ability to sustain operations over an extended period. These challenges underscored the need to develop capacity in the reserve component to support training-base expansion, thus enabling growth, reconstitution, and regeneration efforts that effectively supplement active-duty forces during prolonged conflicts.8

Evolution of processes and policies for force generation and readiness
Figure 1. Evolution of processes and policies for force generation and readiness
(Source: Headquarters, Department of the Army [HQDA], Force Generation-Sustainable Readiness, Army Regulation 525-29 [HQDA, October 2019], 15)

The ongoing Russia-Ukraine War offers critical insights into the demands of high-intensity, protracted conflict—particularly the importance of strategic depth, national mobilization, and resilient reserve structures. Ukraine’s ability to absorb the initial Russian offensive and then counterattack illustrates the importance of maintaining a well-trained and well-equipped reserve component that can rapidly mobilize and integrate into operations. Meanwhile, Russia has demonstrated the importance of strategic depth by reverting to Soviet-style mobilization, reactivating expansion cadre units, and drawing from a mobilization human-resource pool of about two million prior-service personnel, which vastly outmatches the 79,000 soldiers in the Army’s Individual Ready Reserve. Whereas some casualty estimates may be inflated, sources suggest a more measured attrition rate and a recent decline in Russian losses underscores Moscow’s capacity to sustain operations over time.9

In contrast, the Army lacks comparable structures for scalable force generation, having treated sustainment and force-generation formations as trade-offs for decades. Without revitalizing strategic and contingency planning to account for partial through total mobilization, the Army will remain unable to scale the additional stocks, units, and personnel replacements necessary to meet protracted demands. As the Army implements its transformation initiative, these examples highlight the need to reconsider whether the Army’s reduced force structure and current readiness models preclude mobilizing, generating, and sustaining forces for extended periods without reconstituting a strategic reserve force.10

Assessing the Army Reserve’s Current Capabilities and Limitations

Given the Army Reserve’s vital role as part of the Army, the considerations in the previous section clarify the reserve component’s potential roles, structure, and capabilities amid the demands of protracted war. A deeper analysis of the Army Reserve must compare its current capabilities to emerging requirements for LSCO and identify potential friction points. Understanding existing gaps will enable the Army Reserve to develop external (defense and service) and internal (component) recommendations that can enhance the Army Reserve without compromising the Army’s ability to fight and prevail in protracted warfare.

Today’s Army Reserve is a linchpin of the total Army, yet its force structure remains a legacy of post–Cold War dividends driven by the 1993 Offsite Agreement. The agreement restructured the Army’s components primarily into a combat reserve (Army National Guard) and combat support enabler (Army Reserve). The transformation reduced the size of both components significantly, and subsequent efforts continued this downsizing trend. Although effective for recent conflicts, the transitions coincided with force-structure reductions in the active component and forced operationalization in the reserve component. The operational reserve created conditions in which the Army became dependent on the reserve component to meet the Army’s primary purpose—to fight and win our nation’s wars.11

Current Capabilities

The Army Reserve has a significant operational footprint with nearly 175,000 soldiers, 11,000 civilians, and 2,000 units serving in 50 states, five US territories, and 25 countries. The component’s structure concentrates on CS and CSS, providing nearly half the Army’s maneuver support and a quarter of the service’s force-mobilization capacity but using only 6 percent of the total Army budget. The Army Reserve provides units and soldiers to participate in major combat operations, making it an essential part of any response to protracted war.12

The Army Reserve provides unique and essential capabilities for supporting the Army through extended combat operations. Despite comprising 20 percent of the Army’s total end strength, the Army Reserve provides more than half the Army’s force structure in terms of capability, demonstrating the reserve’s specialized and crucial role in the military. Significantly, the Army Reserve is the primary provider of the Army’s early-entry and scalable units for theater-level sustainment. For instance, 59 percent of quartermaster units and 44 percent of transportation units—vital for opening theaters and sustained operations—reside in the Army Reserve. These units play a crucial role in the Army’s rapid response to combat situations, highlighting the Army Reserve’s unique capabilities.13

Another aspect often overlooked is the high proportion of Army Reserve soldiers with advanced degrees in law, engineering, medicine, and information technology, further enhancing these specialized capabilities. This civilian-acquired expertise allows the Army Reserve to provide vital support in complex operational environments, from cyberwarfare to reconstruction efforts in post-conflict zones. These diverse and specialized capabilities make the Army Reserve an invaluable asset in addressing future wars and illustrate opportunities to rethink how the Army integrates multidomain capabilities into the reserve component for LSCO and protracted war.14

Limitations and Challenges

Despite the Army Reserve’s unique strengths and capabilities, it faces substantial limitations and challenges when considering the demands of protracted war. First, the component’s roles, responsibilities, and force structure remain relatively unchanged since it transitioned to an operational reserve in 2008, leaving the Army Reserve ill postured to support large-scale mobilization and force-generation operations. Second, the Army Reserve relies on aggregating personnel to fill deployment shortages, especially in the mid-grade noncommissioned and commissioned officer ranks, forcing the Army to deploy units manned at less than 100 percent or to delay the provision of follow-on units during a large contingency. Third, Army Reserve equipment modernization and maintenance lag significantly behind the active component, creating interoperability and readiness challenges. Finally, Army Reserve training lacks the scale and integration necessary to stress its formations, which provide support at echelons above the brigade and corps levels. Unless the Army Reserve evolves, it risks becoming obsolete in the Army’s transformation into a multidomain operations–capable force and compromising its ability to provide essential CS and CSS support—creating gaps in sustaining the Joint Force during a protracted-war scenario.15

The Army Reserve’s stagnant roles, responsibilities, and force structure pose a major challenge for the Army’s protracted-war preparations, particularly for the Army’s ability to execute mobilization processes efficiently. Whereas the Army Reserve contributes 25 percent of the Army’s force-mobilization capacity, only a limited number of its units are designated to operate mobilization force generation installations (MFGIs), which are essential for processing and deploying forces. The Mobilization Support Force, which includes key enablers such as regional support groups, combat sustainment support battalions, and specialized logistics and administrative units, provides immediate expansion capacity to Army MFGI efforts. But these units are intended to be stopgap measures until contracting solutions take over, and units in the Mobilization Support Force are likely to have follow-on missions overseas during wartime. In a full-scale mobilization for a protracted conflict, the lack of dedicated, trained units could significantly delay or even degrade the Army Reserve’s ability to mobilize and deploy combat-ready forces rapidly.16

The Army Reserve’s practice of using personnel aggregation to fill deploying units highlights a significant limitation in its ability to meet early demands during full mobilization and to sustain force generation during extended combat operations. As casualties increase and operational demands grow, this issue will worsen. The Army Reserve often uses personnel aggregation to address deployment shortages, especially among mid-grade noncommissioned and commissioned officers, which decreases the readiness of follow-on units. In a prolonged conflict, generating additional forces will be challenging due to full mobilization and the expansion of the industrial base, decreasing the availability of personnel. This challenge will force Army leaders to choose between deploying understaffed units early or delaying the deployment of follow-on units by reallocating personnel.17

Additionally, though the Army Reserve supports current recruitment levels with training commands, it cannot meet the training demands of LSCO and recruitment surges. This limitation reflects broader issues resulting from the Army’s cuts to its force-generation structure, which has limited rapid expansibility. Without augmenting its capacity, the Army Reserve will face difficulty supporting the growth or reconstitution of the force.18

The Army Reserve’s challenges with equipment modernization and maintenance significantly impact its preparedness for protracted war. Reserve units often operate with outdated systems, as modernization efforts prioritize the active component, leaving reserve units with aging vehicles, weapons, and communication systems that will hinder Joint operations. Many reserve vehicles and weapons systems are also approaching or have exceeded their intended service lives which will compromise effectiveness and reliability during sustained combat. This disparity hampers interoperability, particularly in high-intensity-conflict scenarios where seamless coordination with active-duty forces is essential.19

Budget constraints and competing priorities within the Army further limit comprehensive modernization efforts, often resulting in incremental rather than systemic improvements. Reserve units often receive piecemeal new equipment fielding as excess vehicles or equipment sets are available. These staggered increments create training, logistical, efficiency, and interoperability challenges as soldiers struggle to maintain proficiency on a mixture of old and new systems. The Army Reserve’s dispersed structure exacerbates this challenge, making fielding new equipment and ensuring uniform modernization across all units difficult. Dispersion also impacts the shipment of equipment to the theater because the Army Reserve maintains limited training equipment at MFGIs. Instead, reserve units must bring their equipment for post-mobilization training, complicating logistics and delaying the unit’s deployment to the theater. This logistical hurdle can require splitting units or reassigning late-deploying forces to manage equipment shipments, thus disrupting cohesion and readiness. Without targeted investments in interoperable systems and a strategic approach to modernization and maintenance, the Army Reserve will remain ill-equipped to sustain operations in a protracted conflict.20

Army Reserve training models are outdated and not tailored to the demands of protracted war, failing to provide the scale, integration, and complexity necessary for sustained, high-intensity operations. The standard training schedule—one weekend per month and two weeks annually—does not allow sufficient time to develop the advanced skills and unit cohesion required for a prolonged conflict. This limited training cadence also restricts opportunities to conduct large-scale, multi-echelon exercises replicating the operational tempo and duration of protracted warfare. For instance, current training does not adequately build collective proficiency at the brigade and division levels, which is essential for coordinating large-scale operations over extended periods.21

The lack of realistic, sustained training scenarios further hinders readiness, as Army Reserve units rarely experience the physical and psychological demands they would face in a long war. Limited cross-training opportunities with active-duty units and other branches intensify integration challenges, potentially weakening the effectiveness of the Joint Force. Addressing these shortfalls requires more integrated, extended, and rigorous training that aligns with the realities of protracted conflict. But budget constraints and employer relationships make extending training periods and increasing participation in large-scale exercises difficult, leaving the Army Reserve disadvantaged in preparing to integrate with active-duty forces in Joint operations.22

Developing Recommendations for Adaptation

Meeting the preceding challenges requires the Army Reserve to heed Lieutenant General Robert D. Harter’s call for a significant transformation to meet the demands of future threats. In Harter’s first letter to the Army Reserve as its 35th chief, he declares, “Given the complexity of the global environment, combined with constrained resources, we must adapt our thinking to overcome near-term challenges, transform our formations and structure to fight and win in LSCO, and modernize our equipment and processes to counter future threats. Be innovative, be bold.” Adapting to meet this call requires the Army Reserve to move beyond an operational reserve model and restore the component’s ability to mobilize, expand, and sustain forces rapidly in a prolonged conflict.23

The Army Reserve needs a comprehensive shift to reestablish a strategic reserve that complements the operational force, ensuring the Army can scale effectively without overextending its active component. The following recommendations address the Army Reserve’s critical gaps in mobilization, force structure, training, and sustainment. If adopted, these recommendations would ensure the reserve component can meet the demands of protracted conflict. This transformation requires reforms at multiple levels because reform must answer the Army’s pacing threats in support of the Joint Force.

Office of the Secretary of War

To prepare for prolonged, high-intensity warfare, the Office of the Secretary of War must evolve the total force policy beyond the current operational reserve model, account for the total force demand in contingency planning, and reinvigorate defense manpower to restore strategic depth. The examples and challenges discussed in the previous section reinforce that the evolving strategic environment will stress legacy rotational force deployments, and large-scale wars will require a deep reserve capable of sustaining long-term mobilization.

First, the Office of the Secretary of War should redefine its operational model, incorporating lessons from Joint war games and concept development. Without clearly articulating the meaning of strategic and operational reserves, the Office of the Secretary of War will increase uncertainty among the Army commands already struggling with force design and development. For example, the Office of the Secretary of War could define operational models using a hybrid- or adaptive-reserve model, where operational reserves align with force requirements for a contingency response in addition to strategic reserve forces meant to mobilize only for a major war. By taking this approach, the service can better optimize its modernization, readiness, and force-structure initiatives to create a balanced force that can adapt to emerging requirements while creating a scalable strategic reserve that prevents the Army from hollowing out the force.

The Office of the Secretary of War should then update its contingency-planning and defense-planning guidance to reflect the adaptive-reserve model. Capturing the total force demand for all contingency plans will be critical to this effort. The office should mandate that planning efforts account for all the forces required to carry out mobilization, force generation, and homeland defense like historic color-coded war plans—not just the force needed to fulfill commanders’ requirements inside their respective theaters. By implementing this recommendation, the Office of the Secretary of War can enable the combatant commands and the Army to identify how gaps in force-generation capacity and competing resourcing demands for apportioned forces pose risks to the mission and the force.

The Office of the Secretary of War must also reinvigorate strategic manpower depth even as the office considers overall cuts and reprioritizes its budget to support a denial strategy. For instance, cuts to the Army structure, which would reduce the number of brigade combat teams, could create risks in the European and Korean theaters unless the service built additional capabilities in combat arms within the reserve component. The office should also consider increasing the amount of pretrained manpower by reinvigorating the Individual Ready Reserve or individual mobilization augmentee programs, which would ensure the availability of skilled replacements to round out units during mobilization and increase Army expansibility.24

Headquarters, Department of the Army

The Army should consider optimizing its force structure and mix to ensure it can sufficiently support mobilization for early war and rapid expansion in sustained conflicts. The current force mix positions critical enablers (such as bulk fuel, theater opening, and so forth) within the Army Reserve, creating early operational gaps. Meanwhile, the active component retains a combat arms structure that maintains higher readiness for later war requirements, creating a strategic imbalance. By shifting light combat arms forces to the Army Reserve or Army National Guard to free up structural space, the Army could improve its flexibility and responsiveness to the early requirements of an Indo-Pacific contingency and build depth for longer wars.

But the Army will need to expand the size of the Army Reserve or determine trade-offs due to uneven force-structure exchanges. A potential solution, albeit one that risks creating a hollow force, would be to convert infantry brigade combat teams into smaller security force assistance brigades (SFAB). Despite current efforts to reduce active and guard SFABs, future reserve SFABs could support episodic security cooperation across combatant commands while also providing a cadre structure for combat arms soldiers to enhance Army expansibility during sustained LSCO.25

An alternative option would be to convert some Army Reserve force-structure spaces into multidomain units specializing in cyber, information advantage, and unmanned systems. The units would help the Army grow its multidomain depth, especially in military occupational specialties, which the active component struggles to generate and retain. The capabilities would also foster better public-private partnerships and readiness by providing trained specialists who actively maintain their proficiency through civilian employment. These adjustments would enable the Army Reserve to help the active component adapt to future requirements and avoid sacrificing strategic depth as it transforms.26

The Army also needs to develop and rehearse a master mobilization and training-base-expansion plan. The plan and exercises (like Proud Saber 82) would help define total force demands for sustained LSCO, including Mobilization Support Force and training-base-expansion units responsible for operating MFGIs and facilitating force expansion. Such planning would also enable the Army to develop an LSCO-specific model for force generation that adapts the Regionally Aligned Readiness and Modernization Model to incorporate a scalable mobilization framework based on the proposed adaptive-reserve model. This framework would enable the Army and its reserve component to tailor their readiness cycles to prioritize the modernization and readiness of operational units during budgeting and execution windows, in addition to forecasting long-term demand during programming to maintain strategic reserve capacity.27

Office of the Chief of Army Reserve

The Office of the Chief of Army Reserve must advocate for the changes discussed in the previous section and seek ways to adapt reserve training and readiness models to prepare combat-ready forces for protracted war. The current readiness model and training cycle do not adequately prepare units for sustained combat. For example, large-scale mobilization exercises are infrequent, limiting the Army Reserve’s ability to test mobilization and rapid force-deployment capabilities at scale. The Army Reserve also faces dilemmas related to storing and maintaining its equipment for training and readiness purposes. Further, unit dispersion and the operational reserve model create difficulty in maintaining equipment and managing talent.

The Office of the Chief of Army Reserve must work with the US Army Western Hemisphere Command and US Army Transformation and Training Command to develop the adaptive-reserve model. The new model would stairstep operational and strategic reserve units, requiring changes to the standard training cycle. The operational units would need to replace the monthly battle-assembly cycle with three one-week and two-week quarterly training periods to allow for more complex collective training. Additionally, the units need prioritized funding to meet higher collective readiness standards before mobilization, as opposed to the current reserve units, which are funded only to maintain lower readiness levels prior to mobilization. The remaining Army Reserve units would keep the current process for the Regionally Aligned Readiness and Modernization Model, focusing on individual and small-unit levels of collective readiness.28

Modernizing training is also essential to prepare USAR units for LSCO and prolonged operations. The Army Reserve’s CS and CSS units typically support echelons above the brigade or corps levels yet train only with other reserve units, thus limiting the value of the training by not stressing unit capabilities. Reserve units should instead participate in fewer but larger multi-echelon combat training exercises nested with combat training center rotations (for example, the National Training Center and Warfighter exercises) to test these units’ capabilities and improve their integration with active-duty units. By combining cross-component training events leveraging synthetic and physical training environments, reserve units could experience the demands of LSCO. Surging reserve units into Army Reserve installations during these larger exercises would also enable the component to assess the readiness of its MFGIs. Implementing scalable, multi-echelon exercises will provide realistic training scenarios that reflect the complexities of protracted warfare and significantly improve the Army Reserve’s ability to integrate seamlessly with active-duty forces for protracted war.29

The Office of the Chief of Army Reserve should also establish and consolidate equipment at regional training centers to improve maintenance capacity and enable unit maneuvers to enhance readiness. Strategically aggregating equipment allows the Army Reserve to reduce real property costs, consolidate maintenance staff to increase efficiency, and repurpose operations and maintenance funding for training or infrastructural improvement. Consolidating equipment would also reduce the impacts of dispersion and help the Army forecast transportation demands (for example, material-handling equipment, contracted support, and pusher units), reducing reserve units’ logistical burdens that distract from post-mobilization training. But the Office of the Chief of Army Reserve must work with the Army and Congress to secure funding to support the consolidation and modernization of the reserve’s training and mobilization infrastructure, including reserve-funded installations like Fort McCoy, Wisconsin, and US Army Support Activity, Fort Dix, New Jersey, to enhance the Army Reserve’s readiness for rapid mobilization and prolonged conflicts.30

The Office of the Chief of Army Reserve must also address the significant personnel shortfalls that impact the Army Reserve’s readiness for protracted war. The adaptive-reserve model allows this office to lead the revitalization of reserve-personnel policies for the Troop Program Units, Individual Ready Reserve, and individual mobilization augmentee because the model fosters a service continuum. This continuum construct would enable flexible movement from operational to strategic reserve units, granting soldiers greater control over their service and benefiting them and their families.

The Army Reserve could reduce the operational tempo for soldiers progressing in their civilian careers and mitigate burnout, particularly in command positions. For soldiers with greater career and time flexibility, the Army Reserve could offer more active-duty service for operational support orders, enhancing readiness within operational units. Prioritizing units would also allow the Army Reserve to forecast individual duty travel and other incentive pay, ensuring high-demand capabilities remain robust and reducing reliance on cross-leveling to fill units before mobilization.

For example, if strategic reserve units primarily focus on homeland defense missions, soldiers could transition to a status like the individual mobilization augmentee, consolidating their annual duty requirements to once per quarter or year to minimize disruptions to the soldiers’ civilian careers. This approach would help retain valuable skills and experience within the Army Reserve, providing flexibility and incentivizing participation through alternative career pathways to retain high-quality personnel. This model will foster a more adaptable and resilient force capable of addressing the diverse challenges of protracted warfare.

Challenges and Risks in Transforming the Army Reserve

Transforming the Army Reserve to meet the demands of protracted warfare is a complex endeavor fraught with significant challenges and risks. Whereas the proposed recommendations offer potential solutions, implementation would involve substantial hurdles, including organizational and bureaucratic resistance which could impede the Army Reserve’s ability to adapt effectively. The Army’s organizational culture, which values tradition and norms established during the 1993 Offsite Agreement, will likely create bureaucratic resistance to reforms that disrupt the status quo. Leaders from the active component and reserve component may oppose changes that threaten those leaders’ authorities or established practices. For instance, expanding the Army Reserve’s combat arms capacity might cause skepticism among active-duty leaders concerned about readiness and deployability. Overcoming this resistance would require clear communication of the strategic rationale for reform, active engagement with stakeholders at all levels, and a shared vision for the future of the Army Reserve.31

Although used often in this article, the terms operational and strategic reserve lack clarity. The Office of the Secretary of War and the Army must define these terms concretely before any transformation of the Army Reserve for protracted war can occur. Without precise definitions, efforts to develop an adaptive-reserve model lack a solid foundation, precluding the alignment of force structure, readiness levels, and mobilization expectations with actual wartime demands.

Currently, the force mix creates unrealistic expectations for Army Reserve units that may be required before C-day or within the first 30 days of a conflict. These units need a waiver from the secretary of war to bypass the standard 30-day notification requirement for involuntary mobilization, effectively requiring them to maintain near-active readiness levels. But, sustaining higher reserve readiness long-term is resource intensive, eliminates the cost-benefit balance, and risks degrading retention, as part-time soldiers struggle to balance their military obligations with civilian careers.

The Army needs a clear framework for force employment. For instance, a strategic reserve could be defined as forces mobilized at or beyond 90 days to provide sustainment and expansion capability, and an operational reserve might encompass forces required within the first 45–90 days to reinforce active units that deploy early. Establishing these thresholds would enable the Army to structure the Army Reserve accordingly, ensuring the right units maintain the appropriate level of readiness without overburdening the force. Without such clarity, the Army Reserve risks being overextended or underprepared, unable to support the Army’s needs in a protracted conflict effectively.

Resource allocation and budgetary constraints pose significant challenges to implementing the proposed reforms. Modernizing equipment, expanding training programs, and upgrading infrastructure require substantial financial investment. Securing sustained funding for these initiatives may prove difficult in an environment of competing priorities and limited resources. This challenge is compounded by the need to demonstrate the long-term, strategic value of these investments, which may not yield immediate, visible results.

Operational challenges also emerge from the need to harmonize training, equipment, and readiness standards between the Army Reserve and active-duty forces. Variances in operational cycles and technological disparities cause friction that must be mitigated through standardized equipment, interoperable systems, and integrated training opportunities. Implementing these changes without disrupting ongoing operations or compromising readiness necessitates meticulous planning and execution. The risk of operational disruption during the transition period is considerable. Rebalancing the force mix or adopting new training regimens may temporarily reduce the level of readiness. A phased implementation and continuous evaluation are crucial to minimize disruptions and ensure the transformation process enhances rather than undermines readiness.

The societal and political implications of the Army Reserve’s transformation must also be carefully managed. Increasing training requirements and expanding roles may strain relationships with civilian employers and reserve soldiers’ families. More frequent mobilizations or extended deployments could disrupt civilian careers, potentially reducing public support for the Army Reserve’s operational reserve units and complicating recruitment and retention efforts. Balancing the demands of military service with civilian obligations remains a critical challenge in implementing reserve reforms, especially when the United States may lack the workforce necessary to expand the Army and industry simultaneously. Despite a desire to have a large military or reserve, increasing demographic pressures might shift the definition of a strategic reserve toward an unmanned or long-range, strike-heavy force.32

In summary, transforming the Army Reserve to meet the demands of protracted warfare requires addressing institutional resistance, overcoming resource constraints, synchronizing training with active-duty forces, managing societal impacts, and mitigating risks to operational readiness. Successfully navigating these challenges is crucial to ensuring the Army Reserve’s relevance and combat readiness. Whereas the path to transformation is fraught with obstacles, the change remains urgent and necessary to prepare the Army Reserve for protracted warfare.

Conclusion

The Army Reserve is crucial for maintaining Army operations during crises and extended conflicts, particularly in great-power competition and potential prolonged, high-intensity warfare. But the current reserve structure, readiness, and role are unsuitable for long, resource-intensive conflicts. This article highlights several factors affecting the Army Reserve’s effectiveness, including unclear strategic and operational reserve roles, an outdated force mix with early-deploying sustainment units in reserves, mobilization inefficiencies, equipment modernization gaps, and training inadequacies. These issues must be addressed to ensure the Army Reserve can support Army mobilization, expansion, and sustainment at sufficient speed and scale for LSCO.

Given the inherent complexity of transforming the Army Reserve to meet future demands, the following recommendations provide a multitiered approach to beginning to restore strategic depth.

  • Office of the Secretary of War. Redefine the total force policy to clarify strategic and operational reserve roles; incorporate partial, full, and total mobilization demand into contingency planning; and revitalize the Individual Ready Reserve and individual mobilization augmentee programs to enhance manpower depth.

  • Headquarters, Department of the Army. Adjust the force mix by moving early deploying sustainment units to the active component and transitioning select combat arms capabilities to the Army Reserve to maintain strategic depth and enable investment in modernization priorities. Planning for and expanding the reserve component Mobilization Support Force and boosting force-generation capacity will ensure the Army can scale during prolonged conflicts.

  • Office of the Chief of Army Reserve. Develop an adaptive-reserve model with training reforms, large-scale mobilization exercises, and equipment consolidation at regional training centers to improve readiness and logistical efficiency. Establish a service-continuum model between operational and strategic reserve units to enable career flexibility and retention, ensuring critical skill sets remain within the force over time.

These recommendations will enhance the Army Reserve’s capability as an adaptive federal reserve, supporting sustained mobilization and multi-echelon operations alongside the active component. Implementing these changes involves overcoming institutional resistance, resource limitations, operational integration challenges, and training constraints. Managing transitions between reserve units and maintaining employer relationships for higher-tempo operational reserve units are crucial to balancing military readiness with civilian careers. Failure to modernize risks repeating past US mobilization challenges in the Korean War and current Russian logistical issues in Ukraine. Drawing lessons from previous conflicts, the United States must integrate strategic depth, adaptive mobilization, and force resilience into reserve transformation efforts. Substantial reforms are necessary for the Army Reserve to meet the demands of LSCO against peer competitors, ensuring the Army is prepared for future conflicts.

 
 

Joshua Yarbrough
Lieutenant Colonel Joshua Yarbrough is a US Army strategist and deputy commander of the US Army Support Activity, Fort Dix, New Jersey. With more than 20 years of Army Reserve service, his experience includes strategic planning roles at US Army Reserve Command and US Army, Pacific Command, along with tactical leadership positions during deployments to Afghanistan and the Middle East. Yarbrough is a recent graduate of the US Army War College resident class of 2025.

 
 

Endnotes

  1. 1. C. Q. Brown to the Joint Force, memorandum, “Message to the Joint Force,” October 3, 2023, https://news.usni.org/2023/10/03/cjcs-c-q-brown-first-message-to-the-joint-force.
  2. 2. Jim Garamone, “Potential for Great Power Conflict ‘Increasing,’ Milley Says,” Department of Defense, April 5, 2022, https://www.defense.gov/News/News-Stories/Article/Article/2989958/potential-for-great-power-conflict-increasing-milley-says/; Strategic Studies Institute (SSI), 2024 Annual Estimate of the Strategic Security Environment (SSI/US Army War College [USAWC] Press, 2024), 39, 41, 48, https://press.armywarcollege.edu/monographs/970; and Rick Berger and Mackenzie Eaglen, “​ ‘Hard Choices’ and Strategy Insolvency: Where the National Defense Strategy Falls Short,” War on the Rocks, May 16, 2019, https://warontherocks.com/2019/05/hard-choices-and-strategic-insolvency-where-the-national-defense-strategy-falls-short/.
  3. 3. Conrad Crane and Gian Gentile, “Understanding the Abrams Doctrine: Myth Versus Reality,” War on the Rocks, December 9, 2015, https://warontherocks.com/2015/12/understanding-the-abrams-doctrine-myth-versus-reality/; and Julie Cameron Rudowski, “Sullivan: Dangers of ‘Hollow Army’ Caused by Sequestration,” Association of the United States Army, August 1, 2013, https://www.ausa.org/articles/sullivan-dangers-hollow-army-caused-sequestration.
  4. 4. Miranda Summers Lowe, “The Gradual Shift to an Operational Reserve: Reserve Component Mobilizations in the 1990s,” Military Review 99, no. 3 (May–June 2019): 118–26, https://www.armyupress.army.mil/Journals/Military-Review/English-Edition-Archives/May-June-2019/Summers-Lowe-Reserve-1990s/; David Barno and Noral Bensahel, “America Is Not Prepared for a Protracted War,” War on the Rocks, December 4, 2024, https://warontherocks.com/2024/12/america-is-not-prepared-for-a-protracted-war/; Ricky D. Gibbs, Determining an Appropriate Force Sizing Paradigm for the U.S. Army (US Army War College [USAWC], May 2004), iii, https://apps.dtic.mil/sti/citations/ADA424184; Dan Driscoll and Randy George, memorandum, “Letter to the Force: Army Transformation Initiative,” May 1, 2025, https://www.army.mil/article/285100/letter_to_the_force_army_transformation_initiative; and Andrew Feickert and Lawrence Kapp, Army Active Component (AC)/Reserve Component (RC) Force Mix: Considerations and Options for Congress, Congressional Research Service (CRS) Report R43808 (CRS, 2014), 7–8, https://www.congress.gov/crs_external_products/R/PDF/R43808/R43808.3.pdf. The overall decrease in force structure following the Cold War coincides with an increasing reliance on the reserve component. But the cuts have remained proportional, meaning even as the active component declines, reserve component structure has not increased.
  5. 5. Mao Tse-Tung, Selected Military Writings of Mao Tse-Tung (Foreign Languages Press, 1967), 209, 210–14; Robert M. Citino, The German Way of War: From the Thirty Years’ War to the Third Reich (University Press of Kansas, 2005), xvi, 149–53; Bryan R. Gibby, Korean Showdown: National Policy and Military Strategy in a Limited War, 1951–1952 (University of Alabama Press, 2021), 281–88; and US Army Training and Doctrine Command, The Operational Environment 2024–2034: Large-Scale Combat Operations, TRADOC Pamphlet 525-92 (Army Training and Doctrine Command, December 2024), 4–5.
  6. 6. Katie Crombe and John A. Nagl, “A Call to Action: Lessons from Ukraine for the Future Force,” Parameters 53, no. 3 (Autumn 2023): 25–26, https://press.armywarcollege.edu/parameters/vol53/iss3/4/; Andrew Feickert, The 2024 Army Force Structure Transformation Initiative, CRS Report R47985 (CRS, August 2024), 1–5; and John Nagl and George Topic, “On (Protracted) War: The Challenge of Sustained Large-Scale Combat Operations,” Modern War Institute, October 9, 2024, https://mwi.westpoint.edu/on-protracted-war-the-challenge-of-sustained-large-scale-combat-operations/.
  7. 7. Andrew J. Forney, “Davy Crockett and the Boy Scouts: The Korean War and Mismanaging Protracted Conflict,” Texas National Security Review 8, no. 1 (Winter 2024/2025): 31–48.
  8. 8. Headquarters, Department of the Army (HQDA), Force Generation-Sustainable Readiness, Army Regulation 525-29 (HQDA, October 2019), 15; Forney, “Davy Crockett,” 32–34; and Andrew A. Brown, Personnel Mobilization for Sustained Large-Scale Combat Operations: The Future Is in the Past (US Army Command and General Staff College, 2021), 1.
  9. 9. Charles McEnany and Daniel S. Roper, “The Russo-Ukrainian War: Protracted Warfare Implications for the U.S. Army,” Association of the United States Army, October 1, 2024, https://www.ausa.org/publications/russo-ukrainian-war-protracted-warfare-implications-us-army; and Olga Ivshina, “How Russia Took Record Losses in Ukraine in 2024,” BBC, May 4, 2025, https://www.bbc.com/news/articles/c5yg4z6v600o.
  10. 10. Brian Kerg, “There Will Be No ‘Short, Sharp’ War. A Fight Between the US and China Would Likely Go On for Years,” New Atlanticist (blog), March 19, 2024, https://www.atlanticcouncil.org/blogs/new-atlanticist/there-will-be-no-short-sharp-war-a-fight-between-the-us-and-china-would-likely-go-on-for-years/.
  11. 11. Feickert and Kapp, Force Mix, 50; US General Accounting Office (GAO), Army Reserve Components: Cost, Readiness, and Personnel Implications of Restructuring Agreement, GAO/NSIAD-95-76 (GAO, March 1995), 1–4; and “Who We Are: The Army’s Vision and Strategy,” U.S. Army, n.d., accessed January 26, 2025, https://www.army.mil/about/.
  12. 12. Hearing on the Posture of the United States Army Reserve, Before the Subcomm. on Defense of the H. Comm. on Appropriations, 118th Cong. (2024) (statement by Jody J. Daniels, Chief of Army Reserve); and Office of the Chief of Army Reserve, Army Reserve at a Glance (Office of the Chief of Army Reserve, 2022), 7–10.
  13. 13. In large-scale combat operations and nonpermissive environments, the Army must reconstitute uniformed sustainment capabilities—long treated as a trade space—because reliance on contractors in the war-on-terrorism era will be neither viable nor sufficient. See Office of the Chief of Army Reserve, USAR Battalion Brigade Pre-Command Course (BBPCC) Presentation (Office of the Chief of Army Reserve, 2025), 5; Under Secretary of the Army, Army Fiscal Year Budget Overview 2025 (HQDA, 2024), 10; and Daniels, Hearing on the Posture.
  14. 14. Tazra Mitchell, “Policy Recommendations on Ways for the U.S. Army Reserve to Better Use Civilian-Acquired Skills” (master’s thesis, Duke University, 2011).
  15. 15. Lewis G. Irwin, A Modern Army Reserve for a Multi-Domain World: Structural Realities and Untapped Potential (SSI/USAWC Press, October 2019), 1–3, 32–41, https://press.armywarcollege.edu/monographs/372/.
  16. 16. Joseph Whitlock, “The Army’s Mobilization Problem,” War Room, October 13, 2017, https://warroom.armywarcollege.edu/articles/armys-mobilization-problem/.
  17. 17. Lawrence Kapp and Barbara Salazar Torreon, Reserve Component Personnel Issues: Questions and Answers, CRS Report RL30802 (CRS, November 2021), 3.
  18. 18. Conrad Crane, “7 Issues the Future of the Army Commission Should Have Spent More Time On,” War on the Rocks, February 25, 2016, https://warontherocks.com/2016/02/7-issues-the-future-of-the-army-commission-should-have-spent-more-time-on/.
  19. 19. Office of the Assistant Secretary of Defense for Readiness, National Guard and Reserve Equipment Report for Fiscal Year 2019 (Office of the Undersecretary of Defense for Readiness, March 2018), 1-1, 1-4; and John E. Whitley, “Underfunding the Army Has Risky Implications,” Association of the United States Army, January 11, 2023, https://www.ausa.org/publications/underfunding-army-has-risky-implications.
  20. 20. “US Army: Vietnam-Era M113 Won’t Be Replaced Until the 2020s,” Military.com, April 3, 2015, https://www.military.com/dodbuzz/2015/04/03/us-army-vietnam-era-m113-wont-be-replaced-until-the-2020s; Gary Grantham, “Top U.S. Army Reserve Leadership Confronts Potential Large-Scale Mobilization Challenges,” Defense Visual Information Distribution Service (DVIDS), September 23, 2024, link; and Association of the United States Army, “GAO: Army Faces Challenges Fielding New Equipment,” Association of the United States Army, August 26, 2024, accessed August 17, 2025, https://www.ausa.org/news/gao-army-faces-challenges-fielding-new-equipment.
  21. 21. Irwin, Modern Army Reserve, 53–57; and Shawn P. Creamer, “The Army’s Training Problem: The Mission Correlation Between Home Station Training and Combat Readiness,” Military Review 101, no. 4 (July-August 2021): 74–87, https://www.armyupress.army.mil/Journals/Military-Review/English-Edition-Archives/July-August-2021/Creamer-Training-Problem/.
  22. 22. John Dzwonczyk and Clayton Merkley, “Through a Glass Clearly: An Improved Definition of LSCO,” Military Review (November 2023): 1–8, https://www.armyupress.army.mil/Journals/Military-Review/Online-Exclusive/2023-OLE/Through-a-Glass-Clearly/.
  23. 23. Robert Harter, letter to the Army Reserve, September 3, 2024, Army Reserve, https://www.usar.army.mil/Leadership/Article-View/Article/631391/lt-gen-robert-d-harter/.
  24. 24. Austin J. Dahmer, Resourcing the Strategy of Denial: Optimizing the Defense Budget in Three Alternative Futures (The Marathon Initiative, 2025), 2; and Kapp and Salazar Torreon, Reserve Component Personnel, 3. A revitalized Individual Ready Reserve should be used as originally intended—to fill 10-, 20-, and 30-level and company-grade officer vacancies—instead of relying on cross-leveling from other Army Reserve Troop Program Units, which is unsustainable in great-power competition. To achieve this goal, the Office of the Secretary of War must reverse post-2016 policies that stripped Individual Ready Reserve soldiers of meaningful ways to earn retirement points and sustain readiness, including eliminating affiliations with a reinforcement training unit, distance learning credit, and centrally funded annual training.
  25. 25. Shifting combat arms units from the Army Reserve creates a talent management gap because the component then lacks feeder units for training and civil affairs units. This shift also deprives the Army of a logical place to cultivate unique civilian talent (outside the 75th Innovation Command) that could significantly augment special operations and security force assistance missions.
  26. 26. Government Accountability Office (GAO), DOD Needs Action Plan to Address Enlisted Personnel Recruitment and Retention Challenges, GAO-06-134 (GAO, November 2005).
  27. 27. Katherine L. Kuzminski and Taren Dillon Sylvester, Back to the Drafting Board: U.S. Draft Mobilization Capability for Modern Operational Requirements (Center for a New American Security, June 2024).
  28. 28. Richard K. Betts, Military Readiness: Concepts, Choices, Consequences (Brookings Institution Press, 1995), 40, 42.
  29. 29. Eric Connor, “Mojave Falcon 25: Army Reserve’s Largest Exercise Ever,” Army Reserve, May 15, 2025, https://www.usar.army.mil/News/Article/4187891/mojave-falcon-25-army-reserves-largest-exercise-ever/.
  30. 30. Kuzminski and Sylvester, Drafting Board; and “Mobilization Force Generation Installation (MFGI),” U.S. Army, December 12, 2024, https://home.army.mil/mccoy/about/mobilization-force-generation-installation-mfgi.
  31. 31. Raphael Semmes Duckworth, The 1993 Offsite Agreement: Undermining Goldwater-Nichols and Special Forces Capabilities (Strategic Studies Institute, US Army War College Press, March 2007), 7, 11–15, https://apps.dtic.mil/sti/citations/ADA467206.
  32. 32. Luke A. Nicastro, The 2024 National Defense Industrial Strategy: Issues for Congress, CRS Report IN12310 (CRS, January 2024).
 
 

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