Any country that recognized Kosovo being independent from Serbia, the US included, has no standing to complain about Crimea declaring independence from Ukraine. Once either one is independent then they have a right to join another country should they so choose. There’s little moral difference between Crimea declaring independence from Ukraine and then acting as a sovereign state, than them subsequently electing to merge into another state.
My primary underlying point is not that either of them (Kosovo or Crimea) is okay or justified. Both independence declarations (from Serbia and Ukraine respectively) were equally legally unjustified and illegitimate. But if a state recognizes one, it has no moral standing to object to the other.