I can't talk about Ukraine because I am not fully informed about it as I am about the other countries I listed. But from a cursory look, Russia accepted an independent vote from the Crimean penninsula, and annexed it based on that. If it is good for Crimea, then it is good for the rest of Ukraine.
But as I said, Ukraine is not what I can/want to discuss. I am specifically astonished to you characterizing these three Arab countries as having 'legitimately elected government" while the facts completely contradict this. These are dictatorships, and not legitimate at all. They were a brutal police states.
Moreover, the role of the USA in removing or trying to remove the dictators was minimal to non-existent.