Madness

 Vladimir Putin has unleashed a war in Europe for the first time in several decades to undermine Ukrainian sovereignty and install a puppet government. His claim that he wants to "demilitarize...Ukraine" means that he wants a Ukraine that is prostrate beneath Russian control. He will likely be able to achieve some measure of this. The Ukrainian military will not be able to withstand a full scale invasion.

Long term control of Ukraine will require a great deal of brutality. The war could be short or it could be long. But any attempt to keep control of Ukraine will run into the same problem that America faced in Iraq: insurgency and guerilla warfare. Ukrainian paramilitary forces will be well supplied by Europe and America and able to keep up a long war against Russian control. Any puppet regime will have to rely on brutal oppression to stay in power. 

In 2014, the Maidan Revolution overthrew pro-Moscow president Viktor Yanukovych with primarily civil disobedience. A Russian-backed dictatorship is unlikely to restrain from using violence to suppress civil disobedience. But if Russia leaves Ukraine, it will quickly revert to a pro-European government that will be generously supplied with Western weaponry. Putin has said he doesn't want to occupy Ukraine, but I struggle to see a way for him to keep Ukraine weak without staying.

The long term consequence for Russia will likely be bleak as well. The world seems remarkably unified in opposing this action. My hope is that the economic consequences on Russia will be brutal and undermine Putin's grip on power, but the latter is unlikely. At the very least, I hope this further isolates Russia as a uniquely malevolent actor on the world stage.

I know several Ukrainian students. I have no idea what to tell them. 

This is a crime against them, and it is a crime against the entire post-World War II peace architecture in Europe.

UPDATE: Also, and sincerely from the bottom of my heart. Fuck these people.