Defending critical infrastructure against attack is vital to the National Security of the United States and is essential to maintaining national economic prosperity. As a symbol and instrument of national power, the U.S. military plays a broad role to protecting and defending the homeland. The military must be prepared and ready to execute homeland defense tasks and provide support to other agencies to protect critical infrastructure. To mitigate the risks to our critical infrastructure, the military, in cooperation and collaboration with other governmental agencies, must maintain a robust defense and protection plan. This paper does not advocate large overt security measures. Instead, it emphasizes the continued importance of defending the Nation’s critical infrastructure by showcasing the layers of complexity and interagency support required to conduct critical infrastructure protection. The paper will make recommendations on how to move forward on defending and protecting our critical infrastructure from a whole of government approach.