“A foreign submarine, presumably belonging to the US Navy’s Virginia class, was detected in the Barents Sea by the alert forces of the Northern Fleet,” a high-ranking source within the Russian Navy’s headquarters told Russian media.

The incident occurred on Thursday. A group of anti-submarine vessels and an anti-submarine Il-38 aircraft were dispatched into the area on a search and trace mission.

“The vigorous action of the anti-submarine forces of the Northern Fleet resulted in the submarine being forced out of the boundary waters of the Russian Federation,” according to the source.

“Contact with the submarine lasted for about 27 minutes and then the American sub left the area,” he added.

Earlier this week, US defense officials said Russian strategic nuclear bombers conducted at least 16 incursions into northwestern American airspace over the past 10 days.

The flights occurred mostly along the Alaskan air defense identification zone, where foreign militaries must announce flights before entering.

The recent incidents come amid heightened US-Russia tensions over the current crisis in Ukraine.

The United States accuses Russia of sending weapons to pro-Russian forces in Ukraine under the pretext of sending humanitarian aid.

In calls with German Chancellor Andrea Merkel and British Prime Minister David Cameron on Saturday, US President Barack Obama said any Russian intervention in Ukraine without Kiev’s authorization would “provoke additional consequences,” the White House said.

On Friday, US Ambassador to the United Nations Samantha Power warned Russia over further unilateral intervention in Ukraine, saying it would be viewed as an “invasion” of the country.

"Any further unilateral intervention by Russia into Ukrainian territory, including one under the guise of providing humanitarian aid, would be completely unacceptable and deeply alarming, and it would be viewed as an invasion of Ukraine," Power said.

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