"Some of my critics reproach me to this day for not having insisted on a legally binding stipulation [in 1990] that would have prevented NATO from expanding into Eastern Europe in the future. But such a demand would have been absurd, even preposterous, because the Warsaw Pact still existed at the time. We would have been accused of destroying it with our own hands."
January 1, 1970
https://en.wikiquote.org/wiki/Mikhail_Gorbachev