In the 21st century, the transatlantic bargain that has framed the relationship between the United States and its NATO allies is under more scrutiny than ever before. In a changed geopolitical environment, one characterized by the complexity of modern military operations, the growing power of China, and a climate of economic austerity in the West, a consensus has emerged on both sides of the Atlantic as to the need for a revised bargain to accommodate the changing dynamics of global politics. Washington is becoming less and less willing to tolerate what it sees as fundamental gaps within the Alliance—in defense spending, capabilities, and military transformation—and is sending clear signals to its European allies, as well as NATO partners, that they must take on a greater share of Alliance burdens, accelerate efforts to generate capabilities and resources, and move away from a deeply-entrenched culture of dependency. European allies are learning they must approach transatlantic relations with a new maturity, and as efforts at multinational defense collaboration accelerate across Europe, there is evidence of a new approach to thinking about transatlantic relations. The transatlantic bargain was a Cold War construct suited to its time; what is required now is a transatlantic bargain that generates a new culture of transatlantic partnership, between the United States, NATO, and the European Union.