Can we just agree on a few things here?
1a) The Crimea vote was neither fair nor legal. Short notice. Shuttering of opposition media. Military intervention and intimidation, and very little in the way of civilized debate.
1b) That having been said, Crimea had long been itching to leave Ukraine, and its separatism is why it was given autonomous status back in the 90's. Had there been a fair and legal vote, Crimea likely would've voted to leave.
(Hey guys? It doesn't have to be so f*cking black and white: You can have an illegitimate referendum that comes to the same conclusion as a legitimate one--though probably not with those kinds of margins--and just because the end result likely would've been the same doesn't make a sham referendum legitimate.)
2) Putin is a egomaniacal dictator who silences opposition media, jails dissidents, and otherwise makes a mockery of democracy. He's a liar and increasingly dangerous.
3) Putin did actively intervene in the Crimea and lied about it. Those "self-defense" forces? They were Russian military. Claims that Russians in Crimea were in danger? False. Those "protestors"? Many crossed the border from Russia to agitate. Putin denied it, but finally admitted to it.
4) Putin is actively intervening in Eastern Ukraine, following pretty much the same playbook as Crimea. Astroturfed "protestors" and "freedom fighters" who are actually Russian agents. He denies them now, but the evidence (and I'm not talking about the photographs) is massive.
5a) Yes, the West has committed past sins, like invading Iraq on false pretenses.
5b) Iraq doesn't matter because this is Ukraine, not Iraq. It's childish logic to argue that past sins in a completely unrelated region on completely unrelated matters somehow justify Putin's actions in Ukraine.
Frankly, I don't give a damn about the past injustices done to the Tatars. Populations have migrated and/or been displaced through all of human history. Crimea is a region whose populations has shifted a number of times through history. It's foolish to try to chase this through time. Should we go further back in time and just hand Crimea back to the Greeks? Should we move the Turks out of Turkey and back to Central Asia where they came from? Should we move the English out of England since they were originally invaders from what is now Germany and return England to its "original" inhabitants who long ago had fled to Scotland and Wales?
It's asinine to use the Tatars as the central point of the Crimean question. Isn't it enough to just point to Putin's outright lies and thuggery and the fact that he's currently the biggest f*cking asshole in Europe?