There are some things that should do well if open war breaks out between Russia and Ukraine, like oil and wheat, but in a risk-off environment, even the things that should do well sometimes tumble.
The one spot you can count on in the worst environments is the yen.
It's the top performing currency today, though perhaps not as much as the risk backdrop would indicate. Perhaps that's owing to the stability in the bond market.
In any case, if there's war, there will be a true flight to quality and the level of uncertainty will be incredibly high. The kneejerk will undoubtedly be to buy the yen.
An interesting spot will be GBP/JPY. This pair has tracked the risk trade closely for months and it topped out ahead of 158.00 this month and has been slumping.
