Two Russian nuclear submarines are on patrol off the East Coast of the USA, according to a report of the New York Times.

The mission of the Russian submarines brings back Cold War memories when such patrolling was a regular occurrence, and has raised concerns with the US military leadership in the Pentagon.

The NY Times quotes a naval historian as saying that the Russians had not brought two nuclear submarines off the US coast in 15 years.

One of the submarines was detected some 200 miles of the US East Coast, whereas the location of the other one is unclear. The Russian submarines are of the Akula ("Shark") class, a counterpart to the US Los Angeles class submarines.

"Anytime the Russian Navy does something so out of the ordinary it is cause for worry. We've known where they were, and we're not concerned about our ability to track the subs. We're concerned just because they are there," a senior Defense Department official is quoted as saying.

The NY Times reminds that the US President Obama and his Russian counterpart Medvedev had a telephone conversation on Tuesday on the occasion of Obama's 48th birthday but says it was unclear whether the patrolling Russian submarines came up in the conversation.