MOSCOW, Sept 8 (Reuters) - Russia has started military drills on the Kuril Islands which will include live firing exercises and involve more than 500 troops, Russia"s defence ministry said in a statement on Wednesday. Last month, Russia said it was expanding its military infrastructure on the islands. read more Part of the chain is claimed by Japan. The territorial dispute over some of the islands dates back to the time when the then-Soviet Union seized them at the end of World War Two, and has kept the two countries from signing a formal peace treaty.