Washington: Russian submarines patrolling off the US east coast are not cause for concern and pose no threat to the United States, the Pentagon said.
"So long as they are operating in international waters -- as, frankly, we do around the world -- and are behaving in a responsible way, they are certainly free to do so and it doesn`t cause any alarm within this building," press secretary Geoff Morrell said at a Pentagon news conference.
US Northern Command issued a brief statement earlier that it was monitoring the submarines, which Morrell said were several hundred kilometres off the eastern coastline.
Morrell said he was unsure if Moscow gave Washington advance notice but the US military "had the means to derive where they were going."
Morrell played down the episode, saying, "While it is interesting and noteworthy that they are in this part of the world, it doesn`t pose any threat and it doesn`t cause any concern."
He acknowledged that US submarines have operated off the Russian coast "from time to time" as well, in international waters.
The New York Times first reported the presence of two Russian nuclear-powered, Akula class submarines off the American coast, the first such move in years that carried echoes of Cold War tensions.