U.S. fighter jets on Monday intercepted a half-dozen Russian warplanes off the coast of Alaska and kept tabs on the aircraft until they left the region, authorities said Tuesday.

The F-22 fighters intercepted four Russian bombers and two Russian fighter planes entering an area designated as the Alaskan Air Defense Identification Zone.

"The Russian bombers and fighters remained in international airspace and at no time did the aircraft enter United States or Canadian sovereign airspace," the North American Aerospace Defense Command (NORAD) said in a statement.

NORAD, headquartered at Peterson Air Force Base near Colorado Springs, Colorado, is a joint U.S. and Canadian effort responsible for protecting North American airspace.

“NORAD’s top priority is defending Canada and the United States. Our ability to deter and defeat threats to our citizens, vital infrastructure and national institutions starts with successfully detecting, tracking and positively identifying aircraft of interest approaching U.S. and Canadian airspace,” said Gen. Terrence J. O’Shaughnessy, the NORAD commander.

NORAD fighters intercepted Russian bombers+fighters entering Alaskan ADIZ May 20. 2x Tu-95s were intercepted by 2x F-22s; a second group of 2x Tu-95+2x Su-35 was intercepted later by 2 more F-22’s; NORAD E-3 provided overall surveillance. The aircraft remained in int'l airspace pic.twitter.com/VrNuSWFOQm — North American Aerospace Defense Command (@NORADCommand) May 21, 2019

Russia's Ministry of Defense acknowledged its planes were in the region — on scheduled training exercises.

"Four #Tu95MS strategic missile carriers of the Russian #AerospaceForces made scheduled sorties over the neutral waters of the Chukotka, Bering and Okhotsk seas, as well as along the western coast of Alaska and the northern coast of the Aleutian Islands," the Ministry of Defense tweeted on Tuesday morning.

"At certain stages of the route, Russian aircraft were escorted by #F22 fighter jets of the #USAF. The total flight time exceeded 12 hours," the ministry said.