US fighter planes intercepted two Russian bombers, including one that buzzed an American aircraft carrier in the western Pacific during the weekend, The Associated Press has learned. A US military official says that one Russian Tupolev 95 flew directly over the aircraft carrier USS Nimitz twice, at a low altitude of about 610 meters, while another bomber circled about 58 miles 93 kilometers out. The official was speaking on condition of anonymity because the reports on the flights were classified as secret. The Saturday incident, which never escalated beyond the flyover, comes amid heightened tensions between the United States and Russia over US plans for a missile defense system based in Poland and the Czech Republic. In Moscow, the RIA Novosti news agency reported Tuesday that the head of the Russian Air Force information service, Alexander Drobyshevsky, said the Russian bombers "were carrying out their assigned flights" and in strict compliance with the international airspace rules. "We are surprised by the noise that has been raised (over the flights)," he was quoted as saying.