Well, the US conquered these countries, killed a lot of Taliban, inc. bin laden, toppled Saddam, installed democracy... admittedly things might have got slightly worse after they left, but that's an ideology problem more than a military one.

But there is a difference. Do the Crimeans see themselves as Russian or Ukranian? Do they care enough to fight a guerilla war? If not, then an analogy to Iraq can't be drawn.