You might be interested in Tatsiana Kulakevich’s backgrounder on the situation in Ukraine at The Conversation (hat tip: The Moderate Voice). Here’s her explanation of the U. S. interest in Ukraine:
With its annexation of Crimea and support for the Donbas conflict, Russia has violated the Budapest Memorandum Security Assurances for Ukraine, a 1994 agreement between the U.S., United Kingdom and Russia that aims to protect Ukraine’s sovereignty in exchange for its commitment to give up its nuclear arsenal.
Putin’s threats against Ukraine occur as he is moving Russian forces into Belarus, which also raises questions about the Kremlin’s plans for invading other neighboring countries.
Military support for Ukraine and political and economic sanctions are ways the U.S. can make clear to Moscow that there will be consequences for its encroachment on an independent country. The risk, otherwise, is that the Kremlin might undertake other military and political actions that would further threaten European security and stability.
Dr. Kulakevich is a native of Belarus. I believe she has ably explained the interest of anti-Russian Belarusians and Ukrainians, I will leave it to the reader whether she has made a good case for a U. S. interest in Ukraine. I will provide some additional perspective and offer a few observations.
Both Ukraine and Belarus have been part of Russia and then the Soviet Union since the 18th century. Prior to that both were part of Poland and prior to that were independent countries only rarely. Ukraine was made a republic of the Soviet Union distinct in the 1950s by Nikita Khrushchev, himself a native of Ukraine.
There is no question in my mind that Russia and Putin are irredentist but Russia is not the Soviet Union and Putin is not Stalin. The Soviet Union was expansionist and millennialist. Over the last several centuries has been attacked by Sweden, Poland, Germany (more than once), France, Japan, China (in 1900), and the United States (in 1918). I’m probably leaving some out. Russia has attacked Ukraine and Georgia (maybe—it’s ambiguous as to who attacked whom). The Soviet Union attacked a lot of countries but, as previously noted, Russia is not the Soviet Union.
Here’s the most recent polling information I have been able to find for Belarus:







