Ukraine is another post war made up country. Check the Wikipedia page for the history of Ukraine and you will see that it was never in existence in the form we know it until after WW1 when several diverse cultures were cobbled together as a Soviet state. There were areas that were overwhelmingly ethnic Russian but calling the area Ukraine meant nothing as it was just all part of the USSR. So if you live in New York and administratively they move your town to Pennsylvania, so what you are still an American. Similarly when this Russian area was made part of Ukraine province the Russians were fine with it as it was all USSR. Only when Ukraine broke away with the dissolution of the USSR did these ethnic Russians find themselves within a nation dominated by a different ethnic group and they have as a minority group wanted out. Both Khrushchev and Brezhnev who led the USSR were from the Russian area of Ukraine but certainly would consider themselves Russians not Ukrainian in the present environment.

So the comment that this is an independent nation is correct but misleading. It is in fact a political structure that threw together ethnic groups that have fought each other for power for centuries. A free election in eastern Ukraine would absolutely result in that area choosing to align with Russia.

This is not about Putin wanting Ukraine's oil. Ukraine is not an oil producer but is in fact dependent on mostly Russia for its oil and natural gas.