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 on Wednesday.
"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 miles (kilometers) 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.
The speedy Akula vessels, which can carry cruise missiles, are attack submarines used for spying, guarding warships and tracking stealth submarines capable of launching nuclear weapons.
Russia neither confirmed or denied that its submarines were patrolling near US territory, but suggested there was undue "hysteria" in this case.
"Activities of Russian submarines in the world's oceans outside their own waters do not violate international maritime law and are within normal practice," a military-diplomatic source told ITAR-TASS news agency.
Russia regularly makes its position on international issues known through unnamed sources quoted by state media, and the country's three main news agencies ran nearly identical reactions to the report, quoting a military-diplomatic source.
"The Russian navy systematically pinpoints the location of NATO submarines, including US Navy submarines, in direct proximity to the territorial waters of the Russian Federation," Interfax news agency quoted the source as saying.
"This however has never been a reason to make a lot of noise in the press," the source said, adding: "Consequently, any hysteria in such a case is inappropriate."
During the Cold war, Moscow and Washington routinely sent submarines near each country's coastline to gather intelligence and track fleet movements.
The patrols near the US Atlantic coastline follow Moscow's symbolic shows of force in the past year, with Russian warships carrying out exercises with Venezuela and Russian bombers buzzing a US aircraft carrier in the Pacific.
President Barack Obama has sought to defuse tensions with Moscow over US plans for a missile defense system in Central Europe.
© 2009 Agence France Presse. All rights reserved.