Andrey, 21, had never held a gun before this week. It came as a shock when he received a phone call telling him he had been called up for military duty.

Two days later, he was sitting on a bus on his way to join an artillery unit of the Donetsk People's Republic, one of two breakaway territories in eastern Ukraine that Russian President Vladimir Putin formally recognized on Monday and brought under Moscow's protection.

In preparation for the possibility of all-out war, the separatists have been telling men age 18 to 55 to take up arms, and even some older men have joined up. Andrey, who enlisted with a student friend, said they had no choice in the matter.