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.