The United States government is giving a great deal of attention to the situation in Ukraine, but it does not seem to be willing to threaten the sort of military action that would make an invasion prohibitively costly for Russian. (This related question ask about one of the U.S. government's main activities: saying what they think is going on in Ukraine.)
I suppose on the one hand talk is cheap, but on the other hand it seems like speaking loudly and carrying a small stick would ultimately make the United States look weak, or at least not fully committed to, e.g., protecting weaker states from stronger states. (I can't work it into a sentence, but the example of the Crimea seems instructive.)
Is the U.S. just trying to deter Russia from invading, or do they expect to have some higher moral standing after an invasion because of the attention they're giving Ukraine now?