From Tim Siwiec:
During the collapse of the Soviet Union, The United States under President Bush Sr provided the Soviet Union a $1 billion dollar loan and guaranteed the US and NATO wouldn't seek to gain influence in Eastern Europe.
Russia has nearly been obliterated 3x in the last 220 years by invasions from Western Europe (Napolean, The Kaiser and Hitler). They consider a buffer between themselves and Western Europe as a political necessity.
President Clinton, upon assuming power, quickly began the process of swallowing up Eastern European countries. It continued under every future President, with President Obama toppling the elected government in Ukraine and replacing it with Zelensky.
During this whole time, ethnic Russians throughout modern Ukraine were being killed by Ukrainian nationals. It was a continuation of the UPA (pro-Nazis Ukrainians in World War 2) policies (they were also killing Poles before/during/after WW2) and why the current Ukrainian military adopted the divisional emblem of the 14th SS Waffen Grenadier Division "Galizien" (SS division raised using Ukrainian volunteers).
Modern Ukraine only includes the currently contested regions of the Crimea and DonBas because Premier Khruschev awarded them to the Ukraine in the early 1950's for the majority of the Ukrainian population ultimately fighting against the Nazis in World War 2. The DonBas region was historically the land of the Cossack Khanates (population removed) and the Crimea was populated by the Crimean Tartars (Population virtually wiped out by series of wars). Those critical regions were only considered part of the Ukraine very recently and are populated by mostly Russians.
Russia has repeatedly told the West that the Ukraine cannot become part of NATO, because this will give the West a "first strike" ability to hit Moscow and other key areas without Russia having any response time. It will end the nuclear stalemate that preserved the peace through the Cold War. It is similar to the Cuban missile crises.
The real losers in this war are going to be the Ukrainians who allowed themselves to be used as a proxy Army to attempt regime change in Russia, and now will have to give up vital economic areas to Russia and turn over their mineral wealth to the US.
There are many other factors at play here, the Minsk Accords, leveraging against China and Iran, but you would need to write a book to discuss it.
