The authors write that newly declassified documents lend credence to claims that Western leaders repeatedly reassured their Soviet counterparts during German reunification in the early 1990s that NATO would not seek to expand eastward. The declassified U.S., Soviet, British, French and German documents show that Mikhail Gorbachev and other Soviet leaders were given "a cascade of assurances about Soviet security" by Western leaders throughout German unification in 1990 and 1991. According to the documents, these negotiations “were not at all narrowly limited to the status of East German territory, and that subsequent Soviet and Russian complaints about being misled about NATO expansion were founded in written contemporaneous memcons and telcons at the highest levels.” Not all European leaders were on the same page, the authors note. French leader Francois Mitterrand told Gorbachev in Moscow that he was actually in favor of "gradually dismantling the military blocs," the authors write, while noting that Mitterrand continued reassuring the Soviet Union that the West must "create security conditions for you, as well as European security as a whole.”

Read the full report and documents at the National Security Archive website.