Probably depends more on the citizenship of those aboard, than the registration.

Personally, I wouldn't.

That also depends on your options.

Keep aware of volcanic acivity. The Kamchatka is the most active volcanic place on the planet, with frequent eruptions that push 50,000' or more. There are 29 active volcanos there, four of which are frequent-flyers on a nearly daily basis, ranging from 12,000' ash to tops above the service ceiling of whatever you're in.

Politics and possible repercusions warrant reconsideration, as I'm sure you're aware.