"The existing crisis with Russia has origins that go far beyond Putin. Russia has a foreign and security blob, just as does the United States, with a set of semi-permanent beliefs about Russian vital interests rooted in national history and culture, which are shared by large parts of the population. These include the exclusion of hostile military alliances from Russia’s neighborhood and the protection of the political position and cultural rights of Russian minorities. In the case of Ukraine, NATO membership for that country implied the expulsion of Russia from the naval base of Sevastopol in Crimea (a city of immense importance to Russia, both strategic and emotional), and the creation of a hard international frontier between Russia and the Russian and Russian-speaking minorities in Ukraine, making up more than a third of the Ukrainian population. The Yeltsin government protested strongly against the start of NATO expansion in the 1990s and Russia accustomed itself without too much trouble to NATO membership for the former Soviet satellites in Central Europe. But from the very beginning of NATO expansion in the mid-1990s, Russian officials and commentators—including liberal reformists—warned that an offer of NATO membership to Georgia and Ukraine would bring confrontation with the West and an acute danger of war. These warnings were echoed by George Kennan, the original architect of the strategy to contain the USSR and the State Department’s greatest ever Russia expert, as well as by Henry Kissinger and other leading American statesmen."
January 1, 1970
https://en.wikiquote.org/wiki/Russia%E2%80%93NATO_relations