April 11 (UPI) -- Japanese fighter jets were scrambled to warn six incoming Russian aircraft flying near Tokyo-claimed airspace, NHK reported Wednesday, local time.
The deployment of the aircraft of Japan's self-defense forces took place on Tuesday after two Russian Tu-95 Bear strategic bombers were seen near Japan's claimed portion of the Pacific Ocean.
Russia then sent two Ilyushin Il-38 fighters to an area near the coast of Hokkaido, Japan's northernmost island, and that same afternoon deployed two anti-submarine warfare aircraft, the Tupolev Tu-142, to the Sea of Japan.
Two of the aircraft, most likely the Ilyushin Il-38 fighters, flew across the Pacific Ocean, then made a U-turn after reaching an offshore area near Tokyo.
The fighter jets returned to Russian territory following a course toward Hokkaido, according to the report.
Japanese airspace was not trespassed, the military said.
Tokyo is on alert for any further provocations in the region, particularly from North Korea.
Pyongyang most recently conducted a missile test that ended in failure, and Japanese Prime Minister Shinzo Abe called the launch a grave threat to national security.
Japan is also coordinating an upcoming joint exercise with the U.S. aircraft carrier Carl Vinson, the Asahi Shimbun reported Wednesday, local time.
The supercarrier is en route to the Korean peninsula, but will make a stopover in Japan to conduct joint training, according to Japan's defense ministry.
The drill is to take place in the East China Sea, in an area west of Kyushu in southern Japan.
North Korea warned of "catastrophic consequences" following the U.S. Navy decision to reroute the Carl Vinson back to the peninsula.