It's an interesting question tbh... Bitcoin isn't really linked to USD, it's an open market. You can use RUR or EUR (and probably other currencies too) to buy BTC directly.
That being said, i think a war could never be good for a currency, however, since BTC would be one of the only globally accepted currencies, i don't think the price would drop... But that's just my gut feeling, i don't have a degree in economics, nor did i took the time to investigate what other currency prices did during previous wars.