If I had been in Obama's place, this is what I would have proposed. Opinions?
If Putin really is only interested in peace, how about US making it a joint effort and sending their own troops to stand and protect alongside the Russian troops. Not in a different area, where there will be tensions between areas protected by Russia and areas protected by US, but right in the exact same areas? Where the troops can mingle, talk, get to know each other, etc. If there is an actual threat of muslim uprising or Ukrainians attacking Russians, there will be more troops on the ground to keep the peace. Putin will get to feel vindicated about being right with regards to the claims about threat to his people, while being in a position of not being able to escalate to a war, with opposing troops being right there. And the actual troops will get to know each other and maybe build some comraderrie, which will hopefully keep them from wanting to shoot each other. At worst, US will have to admit that they just didn't see the possible threat to peace that Putin did.
I would have just had a vote in Crimea for all citizens on whether they actually wanted to join Russia or not, the problem with the people in power now is they both believe they know what's best and they don't give a shit about the opinions of their own people.
Here in the UK we're going to be having a referendum on the EU ( which I can't wait to vote on ) and the scots are going to have a vote on independence because the political pressure is so much that Cameron is going to have to do it, but of course he's trying to convince everyone and himself that Scotland needs the UK and that the UK should remain in the EU because it's in 'our' interest.
There is nothing more that a government or leader fears than somebody voting in total opposite to what they've constantly been touting is the 'best' decision for everybody, they hate it when people actively tell them to fuck off through the polls, an example of this is when Nick Clegg tried to push through a referendum on the Alternative Voting system, I think we came close to have 70% of the votes in the UK against it including me voting no.
I doubt the Ukraine government or anyone would ever allow such a move, because then that would mean all the politicians would be wrong, including Putin and Obama, because lets face it, Putin is most likely just using the Crimea as an excuse so if he says he wants to 'protect' the Ukraine as well and everybody votes against him he's going to have some explaining to do, I have of course not discounted the fact that there are lots of Russian ethnics in Crimea who would want to join the federation but if Russia was really that popular elsewhere in the Ukraine there wouldn't be all these problems in that country.