This is a multipronged incursion that assails the very soul of the Russo-Ukrainian nation. They fomented and facilitated sectarianism leading to this tumultuous civil calamity, now they're sadistically spectating, cheerleading what they instigated, doctoring the media reporting of the events and are disseminating fallacious biased distortions of the truth as a tactical platform to reprimand/further vilify the Russians.
War for power ,oil and money
As Unorthodox said, the Ukrainian charlatans in Kiev are lunatics and fascists getting money from the U.S. Incidentally they have been killing the self-defense forces in the east who are Russian speaking.
in short: war between those wo want to start something new and those who don't want them to have it.