The Russian side has not yet released an official statement on the incident, which comes at a tense time in relations with Washington, in particular over the Pentagon's controversial plans to deploy missile defense elements in Poland and the Czech Republic.
According to the reports, one Russian Tu-95 Bear bomber flew 610 meters (2,000 feet) above the USS Nimitz aircraft carrier to the south of Japan, and another circled 50 nautical miles (93 kilometers) from the ship. Four F/A-18 Hornet strike fighters were launched to escort the Russian jets away from the area.
Before the reports emerged, Russia's Air Force had said that on Saturday four Bear bombers conducted patrol flights over the Pacific. Colonel Alexander Drobyshevsky, an aide to the Air Force commander, said that during a long-range flight, the bombers were accompanied by Japanese F-15 fighters and F-18s launched from the Nimitz. He said the flights were conducted in strict adherence with international law.
However, the reports said Japan has filed an official complaint with Russia's Embassy in Tokyo, accusing the Russian bombers of violating Japanese airspace over an uninhabited island to the south of Tokyo.
The Russian bombers were launched from Ukrainka air base in Russia's Far East.
Interceptions of combat aircraft were a common occurrence during the Cold War, but became a rarity when Russia abandoned permanent long-range patrol flights after the collapse of the Soviet Union. The last such incident was in July 2004, when a Bear bomber buzzed the USS Kitty Hawk in the Sea of Japan.
Russia resumed strategic bomber patrol flights over the Pacific, Atlantic, and Arctic oceans last August, following an order signed by President Vladimir Putin. The move was widely seen as a sign of Russia's increasingly aggressive military stance.
In addition to Russia's opposition to U.S. plans to deploy 10 missile interceptors in Poland and a radar in the Czech Republic, relations between the countries have been strained by Russia's decision late last year to impose a unilateral moratorium on the Conventional Forces in Europe Treaty, a key arms reduction pact, as well as by NATO's expansion into the former Eastern Bloc.
In a speech last Friday, President Putin blamed the West for unleashing a new international arms race.