You're making a poor assumption or 3 here. Membership

Posted on: August 19, 2025 at 18:04:27 CT

of Poland was a major problem for Russia, an "existential threat" as it were. Ukraine was a big straw on a broken camel's metaphoric back.

https://afsa.org/did-nato-expansion-really-cause-putins-invasion

Twenty-three years later, President Putin has made Ukraine’s preliminary steps to joining NATO the principal grounds for the Russian invasion of Feb. 24, 2022. The alliance’s leaders have always made clear that it is up to each European country to make its own decision about membership. But the eastward expansion of NATO particularly inflamed Putin, who has claimed that Secretary of State James Baker and other Western leaders assured Soviet President Mikhail Gorbachev in 1990, at the time a unified Germany joined NATO, that the alliance would expand “not one inch eastward.”

George Kennan would surely have understood Putin’s reaction. The architect of the “containment” policy toward the Soviet Union wrote in 1997 that “expanding NATO would be the most fateful error of American policy in the entire post–Cold War era.” Kennan continued: “Such a decision may be expected to inflame the nationalistic, anti-Western and militaristic tendencies in Russian opinion; to have an adverse effect on the development of Russian democracy; to restore the atmosphere of the Cold War to East-West relations; and to impel Russian foreign policy in directions decidedly not to our liking.”

What you just laid out was 2 decades of the US/NATO cornering Russia, with Ukraine being a bridge insanely too far.

"A Russian Sphere of Influence
According to Stephen Kotkin, a professor of Russian history at Princeton University, Putin believes that Russia rightfully deserves a sphere of influence in its “near abroad.” To Putin, Ukraine is not a state because it is not sovereign. Small or weak states are only instruments in the hands of the great powers. Where we see Moscow’s aggression, Putin sees defense. If Russia cannot control Ukraine, then the West will. Thus, countries like Ukraine become platforms for invasion. And then the West will dismember Russia as the USSR was dismembered.

This way of thinking in Russia goes back to the tsars. Russia has no natural borders on its periphery. Stalin believed that without hegemony in Eastern Europe he would be subject to infiltration and subversion. But the peoples of Eastern Europe did not want to be forced to live under communism, and thus arose the very hostility Stalin feared.

In a similar vein and updating this explanation of Soviet aggression, my Ukrainian friends offer another rationale for Putin’s attack. As an autocratic leader who has denied his people the human rights we in the West enjoy, such as a free press, an honest judiciary, and especially genuinely contested elections, he is threatened by a liberalizing Ukraine right on his border. After all, Putin’s 22-year tenure rests on banning free and fair elections, stifling dissent, and controlling domestic media, along with official propaganda that excoriates Western institutions and values."