A Russian nuclear-powered attack submarine cruised within 200 miles of the East Coast recently in the latest sign Russia is continuing to flex its naval and aerial power against the United States, defense officials said.

The submarine was identified by its NATO designation as a Russian Seirra-2 class submarine believed to be based with Russia’s Northern Fleet. It was the first time that class of Russian submarine had been detected near a U.S. coast, said officials who spoke on condition of anonymity because of the sensitive nature of anti-submarine warfare efforts.

One defense official said the submarine was believed to have been conducting anti-submarine warfare efforts against U.S. ballistic and cruise missile submarines based at Kings Bay, Georgia.

A second official said the submarine did not sail close to Kings Bay and also did not threaten a U.S. aircraft carrier strike group that was conducting exercises in the eastern Atlantic.

Kings Bay Naval Submarine Base, north of Jacksonville, Fla., is homeport for two guided missile submarines and six nuclear missile submarines. The submarines are known to be a target of Russian attack submarines.

Meanwhile, the officials also said that a Russian electronic intelligence-gathering vessel was granted safe harbor in the commercial port of Jacksonville, Fla., within listening range of Kings Bay.

The Russian AGI ship, or Auxiliary-General Intelligence, was allowed to stay in the port to avoid the superstorm that battered the U.S. East Coast last week. A Jacksonville Port Authority spokeswoman had no immediate comment on the Russian AGI at the port.

"A Russian AGI and an SSN in the same geographic area as one of the largest U.S. ballistic missile submarine bases—Kings Bay—is reminiscent of Cold War activities of the Soviet navy tracking the movements of our SSBN's," said a third U.S. official, referring to the designation for ballistic missile submarines, SSBN.

"While I can't talk about how we detected it, I can tell you that things worked the way they were supposed to," the second official said, stating that the Russian submarine "poses no threat whatsoever."

According to naval analysts, the Russian attack submarine is outfitted with SS-N-21 anti-submarine warfare missiles, as well as SS-N-16 anti-submarine warfare missiles. It also is equipped with torpedoes.

The U.S. Navy deploys a series of underwater sonar sensors set up at strategic locations near the United States that detected the submarine sometime late last month.

The submarine is currently believed to be in international waters several hundred miles from the United States.

The official said the deployment appeared to be part of efforts by the Russian navy to re-establish its blue-water naval power projection capabilities.

Naval analyst Miles Yu, writing in the newsletter Geostrategy Direct, stated that Russia announced in February it is stepping up submarine patrols in strategic waters around the world in a throwback to the Soviet period.

"On June 1 or a bit later we will resume constant patrolling of the world’s oceans by strategic nuclear submarines," Russian Navy Commander Adm. Vladimir Vysotsky was quoted as saying Feb. 3.

During the Cold War, Moscow’s submarine forces carried out hundreds of submarine patrols annually to maintain its first- and second-strike nuclear capabilities. By 1984, the Soviet Union was declining but its naval forces conducted 230 submarine patrols. Today the number is fewer than 10 patrols.

Richard Fisher, a military analyst with the International Assessment and Strategy Center, said Russian submarine patrols in the Atlantic have been reduced but remain "regular."

"As was their primary mission during the Cold War, Russian SSNs [nuclear attack submarines] would likely be trying to track U.S. nuclear missile submarines deploying from Kings Bay, Ga., and to monitor U.S. naval deployments from Norfolk, Va.," Fisher said in an email.

While the Sierra-2 is comparable to the U.S. Los Angeles-class attack submarine, Russia is building a new class of attack submarines that are said to be comparable to the latest U.S. Virginia-class submarines, Fisher said.

The submarine deployment followed stepped-up Russian nuclear bomber activity near U.S. borders last summer, including the transit of two Bear-H strategic bombers near the Alaska air defense zone during Russian strategic bomber war games in arctic in late June.

Then on July 4, in an apparent Fourth of July political message, a Russian Bear-H flew the closest to the U.S. West Coast that a Russian strategic bomber had flown since the Cold War when such flights were routine.

In both incidents, U.S. military spokesmen sought to downplay the threat posed by the air incursions, apparently in response to the Obama administration’s conciliatory "reset" policy of seeking closer ties with Moscow.

U.S. and Canadian interceptor jets were scrambled to meet the Russian bombers during the flights last summer.

The officials did not provide the name of the Russian submarine. However, the sole Sierra-2 submarine still deployed with Russia’s Northern Fleet is the nuclear powered attack submarine Pskov that was first deployed in 1993.

Confirmation of the recent Sierra-2 submarine deployment followed a report from U.S. national security officials who said a more advanced and harder-to-detect Russian Akula-class attack submarine had sailed undetected in the Gulf of Mexico in August.

Chief of Naval Operations Adm. Jonathan W. Greenert, in response to the report first published in the Free Beacon, stated in a letter to Sen. John Cornyn (R., Texas) that "based on all of the source information available to us, a Russian submarine did not enter the Gulf of Mexico."

Navy spokesmen did not say whether an Akula had been detected elsewhere in the Atlantic around that time period.

A Navy spokesman said later that the last time an Akula was confirmed as present near the United States was 2009.

The U.S. is not the only country responding to increased Russian strategic bomber activity.

Norway’s military has detected an increase in Russian strategic bomber flights near its territory, the most recent being the flight of a Bear H bomber on Sept. 11 and 12 that was shadowed by NATO jet fighters.

Norwegian Lt. Col. John Espen Lien told the Free Beacon in an email that the number of Russian bomber flights this year was more than in the past, with 55 bombers detected.

According to Norwegian military data, Russian aircraft flights near Norwegian coasts began increasing in July 2007 and increased from 14 flights in 2006 to 88 in 2007. There were 87 in 2008 and 77 in 2009 and a decline to 37 in 2010 and 48 in 2011.

"Most of these strategic flights are … Tupolev TU-95 Bear [bombers]," he stated. "In 2007 (and partly 2008) we also identified some TU-160 Blackjack. Lately we have also identified some TU-22 Backfire."