MOSCOW — The Russian military said Tuesday that its bombers' flyover of a U.S. aircraft carrier in the Pacific was part of a routine patrol conducted in accordance with international rules.

Russian air force spokesman Alexander Drobyshevsky said in a statement carried by Russian news wires that the Tu-95 bombers didn't violate any rules of engagement when they flew over the Pacific on Saturday.

U.S. military officials said that one Tu-95 buzzed the aircraft carrier USS Nimitz twice, at a low altitude of about 2,000 feet, while another bomber circled about 50 nautical miles out. U.S. fighters were scrambled from Nimitz to intercept the bombers.

Drobyshevsky said the Russian bombers conducted their flight "in strict compliance with the international rules of using airspace rules, over neutral waters and without any violation of other countries' borders." He said the bombers were fulfilling their "assigned task" when they were escorted by the U.S. carrierborne fighters.

The Saturday incident came amid heightened tensions between the United States and Russia over U.S. plans for a missile defense system based in Poland and the Czech Republic.

The U.S. has defended the plan as necessary to protect its European allies from possible attacks by Iran. But the Kremlin has condemned the proposal, saying it would threaten Russia's security.

Such Russian encounters with U.S. ships were common during the Cold War, but have been rare since then. Russia's President Vladimir Putin Russia revived the Soviet-era practice of long-range patrols by strategic bombers over the Atlantic, Pacific and Arctic oceans last August.