During negotiations over German reunification in 1990, did the United States promise the Soviet Union that NATO would not expand into eastern Europe? The answer remains subject to heated debate. Today, Moscow defends its invasion of Ukraine by claiming that NATO reneged on a promise to stay out of Russia’s backyard. Skeptics, meanwhile, counter that Russian claims are a pretext for aggression; in their view, Washington and its allies never formally committed to forego NATO expansion.
The skeptics are correct that the two sides never codified a deal on NATO’s future presence in the east. But they misinterpret the precise implications of negotiations that took place throughout 1990. After all, scholars and practitioners have long recognized that informal commitments count in world politics. This was particularly true during the Cold War: as the historian Marc Trachtenberg has shown, the Cold War settlement itself emerged from European, Soviet, and U.S. diplomatic initiatives in the late 1950s and 1960s that were not formalized until nearly a decade later.
However problematic its recent behavior, then, Moscow has reason to argue that the West broke a promise. As declassified U.S. documents show, the George H. W. Bush administration and its allies worked hard to convince Soviet leaders that Europe’s post–Cold War order would be mutually acceptable, as the Soviet Union would retrench and NATO would remain in place. Yet U.S. policymakers may not have intended to make this vision a reality. And although there are many reasons to criticize recent Russian behavior, Russia may not be lying when it claims that a promise was broken. In the end, the United States overturned the system it promised to bring about.
To understand the nature of Western guarantees, a brief timeline is in order. The story begins in the months after the fall of the Berlin Wall, as policymakers struggled to determine whether and how a divided Germany might reunify. By early 1990, U.S. and West German officials decided to seek reunification.