I have my own issues with the invasion of Iraq. I think everyone is in agreement that it was a dumb idea and it should of never happened. Okay, that being said, i am a realist when it comes to stuff like this. This is the situation that we have and now we have to ask ourselves, how do we solve it? As you say, they "should be left to their own devices," I agree that we should have originally done that but now with ISIS, things are different. ISIS is an international threat, the old Iraq was not, this is what makes this different so i am simply proposing how we solve this issue. I'm not speculating what should have been, I'm speculating what we should do now.
Let's just forget about a certain country breaking International law and invading the Ukraine, ISIS is the real issue here?
This is an international issue as well and we should (and are) putting pressure on the russians to stop their actions. I will say this though, the people of crimea and eastern ukraine are very much pro-russia so if they want to be a part of russia, i honestly don't care.