Your imagery alone raises the other risk we face, that Russians will intervene to save their ethnic kin. Any way you look at it we lose: (a) if our military response is insufficient, we get bogged down in another Vietnam morass with all the ludicrous waste that entails; (2) if our military response is sufficient to vanquish the Serbs, then the Russians will be outraged -- in which case we'll be *lucky* if the only result is another cold war (a prospect, BTW, that the Economist seems to welcome -- see the current issue).
Carl Remick