MOSCOW (AFP) - Japan scrambled fighter planes Wednesday to intercept Russian bombers on a training exercise over the Sea of Japan, Russian news agencies reported, quoting a senior Russian air force official. "Four Japanese air force F-15 fighters escorted the strategic aviation crews as they flew over the Sea of Japan," Lieutenant-Colonel Vladimir Drik was quoted as saying by the Interfax and RIA Novosti news agencies. Two Russian Su-27 fighter jets were also sent up to join the bombers after the Japanese intercept to ensure that the Russian Tu-22 bombers, known in NATO parlance as "Backfire" bombers, completed their mission as planned, he said. The Russian bombers were sent on the patrol as part of Russia's "Stability 2008" military manoeuvres in the region, the reports quoted Drik as saying. He added that the two US-made F-15 Japanese fighters had been scrambled from separate bases in Japan to keep an eye on the Russian aircraft. "All flights by air force planes have been, and are being, carried out in strict compliance with international law in airspace over neutral waters and not violating borders of other states," Drik said. Russian strategic bomber patrols stopped with the 1991 collapse of the Soviet Union. After a 16-year hiatus, however, Moscow announced last year that they would resume such flights around the world, citing a need to train crews and respond to similar US flights near Russian borders that were never suspended.