The intercepts come less than two weeks after US bombers were met by Russian jets over the Black Sea.

North American Aerospace Defense Command said US F-22 Raptors intercepted a Russian bomber formation early Wednesday that came within 20 nautical miles (37 kilometers) of the Alaskan coast.

The formation consisted of two TU-95 bombers, two SU-35 fighter jets and an A-50 airborne early warning and control aircraft, NORAD said.

The second formation consisted of two TU-95 bombers and an A-50 and came within 32 nautical miles (60 kilometers) of Alaskan shores.

NORAD said the Russian warplanes remained in international airspace at all times and did not enter US airspace.

The United States maintains an Air Defense Identification Zone off of Alaska which extends beyond national territory to allow for a response to possibly hostile incursions.

"Flying air patrols protects the approaches to our nations and sends a clear message we continue executing our homeland defense missions with the same capability and capacity we always bring to the fight," NORAD commander General Terrence O'Shaughnessy said in a statement.

The Russian defense ministry said on May 29 that two US B-1B bombers had been intercepted by Russian warplanes during a flight over the Black Sea.