Two U.S. F-22 fighter jets intercepted six Russian military airplanes that were flying near Alaska, military officials said Friday.

Lt. Col. Michael Jazdyk, a spokesman for the North American Aerospace Defense Command, or NORAD, said the jets intercepted the planes about 55 nautical miles from the Alaskan coast at about 7 p.m. Pacific time Wednesday.

Tensions are high between the United States and Russia as the two countries are increasingly at odds over Ukraine, where Russian-backed insurgents have been fighting for control of parts of the country.

The Russian planes were identified as two IL-78 refueling tankers, two Mig-31 fighter jets and two Bear long-range bombers. They looped south and returned to their base in Russia after the U.S. jets were scrambled.

At about 1:30 a.m. Thursday, two Canadian CF-18 fighter jets intercepted two of the long-range Russian Bear bombers about 40 nautical miles off the Canadian coastline in the Beaufort Sea.

In both cases, the Russian planes entered the Air Defense Identification Zone, which extends about 200 miles from the coastline. They did not enter sovereign airspace of the United States or Canada.

Jazdyk said the fighter jets were scrambled “basically to let those aircraft know that we see them, and in case of a threat, to let them know we are there to protect our sovereign airspace.”

In the past five years, jets under NORAD’s command have intercepted more than 50 Russian bombers approaching North American airspace.

NORAD is a binational American and Canadian command responsible for air defense in North America.

Reuters and The Associated Press contributed to this report.

Meanwhile, the Russian Su-24 that buzzed the USS Donald Cook carried neither bombs nor missiles but only a basket mounted under the fuselage, which, according to the Russian newspaper Rossiyskaya Gazeta [2], contained a Russian electronic warfare device called Khibiny.

As the Russian jet approached the US vessel, the electronic device disabled all radars, control circuits, systems, information transmission, etc. on board the US destroyer. In other words, the all-powerful Aegis system, now hooked up - or about to be - with the defense systems installed on NATO’s most modern ships was shut down, as turning off the TV set with the remote control.

The Russian Su-24 then simulated a missile attack against the USS Donald Cook, which was left literally deaf and blind. As if carrying out a training exercise, the Russian aircraft - unarmed - repeated the same maneuver 12 times before flying away.

After that, the 4th generation destroyer immediately set sail towards a port in Romania.

Since that incident, which the Atlanticist media have carefully covered up despite the widespread reactions sparked among defense industry experts, no US ship has ever approached Russian territorial waters again.

According to some specialized media, 27 sailors from theUSS Donald Cook requested to be relieved from active service.

Vladimir Balybine - director of the research center on electronic warfare and the evaluation of so-called "visibility reduction" techniques attached to the Russian Air Force Academy - made the following comment:

"The more a radio-electronic system is complex, the easier it is to disable it through the use of electronic warfare."