That's a very strong possibility during a nuclear exchange, and one some of Russia's military hierarchy have talked about.
Also this from a recent FR thread: Supervolcanoes likely triggered externally
For more than a year, ominous rumors had been privately circulating among high-level Western leaders that the Soviet Union had been at work on what was darkly hinted to be the ultimate weapon: a doomsday device. Intelligence sources traced the site of the top secret Russian project to the perpetually fog-shrouded wasteland below the Arctic peaks of the Zhokhov Islands. What they were building or why it should be located in such a remote and desolate place no one could say.
Not having looked this up again, but there is a super-volcano in the Siberian region every bit as dangerous as Yellowstone - what is good for the goose is good for the gander - be careful what you aim at, the other guy is aiming at you.