• The warplanes included Tu-95 bomber and Su-30 and Su-35 fighter aircraft
  • The first intercept took place Monday when 2 American F-16 warplanes tracked four Russian aircraft
  • Last October, U.S. F-16 warplanes intercepted 2 Russian bombers near Alaska

Russian military aircraft were spotted near the state of Alaska for the second time in a week, the joint U.S.-Canadian North American Aerospace Defense Command (NORAD) said Thursday.

American warplanes intercepted the four Russian planes Tuesday, NORAD said in a statement, adding the warplanes included Tu-95 bomber and Su-30 and Su-35 fighter aircraft.

"Russian aircraft remained in international airspace and did not enter American or Canadian sovereign airspace," it said. "NORAD... assesses that this Russian flight activity is in no way related to recent NORAD and US Northern Command operations associated with airborne objects over North America during the last two weeks."

According to NORAD, it uses "a layered defense network" of satellites, ground and airborne radars and fighter jets to track such aircraft. The Alaskan NORAD Region can detect "what goes on in and near North American airspace 24 hours a day, seven days a week," according to its website.

The first intercept took place Monday when an aircraft made visual or electronic contact with another plane. Two American F-16 warplanes were sent to intercept four Russian aircraft.

The recent rare offensive action for warplanes stationed in North America comes at a time when a U.S. aircraft has shot down an alleged Chinese spy balloon and three unidentified objects this month.

Last October, U.S. F-16 warplanes intercepted two Russian bombers in international airspace near Alaska.

Meanwhile, as military tensions continue to mount in Ukraine, General Mark Milley, Chairman of the U.S. Joint Chiefs of Staff, said he believes the war will end at the negotiating table.

"It will be almost impossible for the Russians to achieve their political objectives by military means. It is unlikely that Russia is going to overrun Ukraine. It's just not going to happen," Milley said in an interview with Financial Times. "It is also very, very difficult for Ukraine this year to kick the Russians out of every inch of Russian-occupied Ukraine. It's not to say that it can't happen... But it's extraordinarily difficult. And it would require essentially the collapse of the Russian military," he added.

The war in Ukraine has been ongoing for nearly a year now.

Russia Fighter Jet
The Russian aircraft intercepted the U.S. Navy plane in close proximity causing vibrations and turbulence. Pictured, Russian Sukhoi Su-27 jet fighters perform during an air show St. Petersburg, April 25, 2015. Getty Images/Olga Maltseva