Senate Republicans say that President Barack Obama should find out why Russia has sent two attack submarines on missions along the U.S. Eastern Seaboard.

The Navy has tracked the two nuclear-powered Akula class subs with sonar and aerial surveillance but does not know what exactly the vessels are doing just outside U.S. territorial waters, say members of the Senate Armed Services Committee.

“They’ve been off the coast of Georgia,” said Sen. Saxby Chambliss (R-Ga.), a member of the Armed Services panel. “It’s one of those things we have to watch very carefully.

“I certainly would expect someone to ask them what’s going on,” he said. “Somebody at the Pentagon should be asking that.”

Chambliss said that the subs have been careful to stay in international waters, which begins 12 nautical miles from the coastline.

The Russian vessels are attack subs, designed for sinking warships and other submarines. Lawmakers said their concern would be greater if the subs had the capability to launch intercontinental ballistic missile strikes.

Russia is flexing its military muscle at a time when some politicians have questioned its economic strength. At the end of last month, Vice President Joe Biden said the Russian economy is “withering” and that will force it to accommodate Western nations on national security issues.

Sen. John McCain (Ariz.), the senior Republican on Armed Services, said “it would be good to ask” the Russians what they intend by sending two subs trolling along the coast.

“The Russians have the right in international waters but it is a sign of the reassertion of the Russians’ military presence,” said McCain.

Obama spoke by phone with Russian President Dmitri Medvedev last week, but lawmakers don’t know whether the leaders discussed the subs.

Sen. Kit Bond (Mo.), the senior Republican on the Senate Intelligence Committee, said the presence of the subs is “very troubling.”

Bond called it a “borderline” provocation and “of concern” but declined to say what he will advise the administration to do in response.

Defense experts see Russia as trying to re-establish its military credentials after a string of mishaps. Medvedev recently fired Gen. Nikolai Solotsov as commander of the Russian Strategic Rocket Forces following several failed tests of the submarine-launched Bulava intercontinental missile.

The reputation of the Russian sub fleet hit a low point in 2000 when the nuclear cruise missile sub Kursk sank during a training mission, killing more than a hundred crew members.

Peter Singer, a senior fellow specializing in national security at the Brookings Institution, said the mission shows a military capability not seen from the Russians in recent years.

“It is a little bit of muscle-flexing by them but not all that muscular a muscle-flexing,” said Singer. “It’s a reminder that they are there and that they still have capabilities that few other nations have. They want to be treated like a superpower still.”

For some observers, the presence of Russian subs off the U.S. coast has conjured memories of the Cold War, but Singer said: “We’re not talking about this as a Cold War redux.”

In 2007, Russia resumed long-range air patrols of strategic bombers, another practice discontinued with the end of the Cold War. In 2008, Russia stepped up the patrols, which have flown up to the edge of NATO airspace. Also last year, two Russian bombers flew directly over an American aircraft carrier in the western Pacific, forcing commanders aboard the ship to scramble intercepting fighter planes.

“Basically, I think you don’t want to overreact,” said Lawrence Korb, a former assistant secretary of Defense who now serves as senior adviser to the Center for Defense Information. “The Russians are trying to demonstrate they’re still relevant. The key is we’re tracking them.”