Pentagon spokesman Geoff Morrell said U.S. officials see the patrols as a way of Russia's displaying its force, CNN reported.
"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," Morrell said.
Russia has not ventured near the U.S. seaboard in years, an unnamed senior defense official told CNN.
"What's interesting is, they haven't been able to do this in some time, and now they are," the official said. "It indicates a return to their ability to do this."
The Pentagon's statements came a day after a Russian general dismissed concerns about two Russian submarines seen off America's East coast, calling the subs' patrols routine.
The nuclear-powered submarines' patrols could indicate a more aggressive Russian military stance, The Washington Post reported Wednesday.
But senior General Anatoly Nogovitsyn, deputy chief of staff of the Russian armed forces, said American officials know such patrols are routine and no cause for alarm.
"I don't know if there is any news in this news for anyone," he said. "The fleet shouldn't sit on its hands and be idle."
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