After eight years of this civil war, Russia began defending the people who preferred close relations with Russia and rejected the western influence.
Obviously, Russia escalated the war by attacking Ukraine, but this was hardly a sudden move, and there was a lot of meddling going on by the US.
There was no fighting by anyone, except for Yanukovych attacking Maidan protestors, until Putin sent arms and forces into the east. The US supported Yanukovych’s removal, but there is no way the US could have gotten tens of thousands of protestors to risk their lives at Maidan. The push to get rid of Yanukovych came from the Ukrainians themselves. Russia sent arms and troops into Ukraine in 2014, there was no “civil war.”