Image copyright PA Image caption Russian fighter jets were intercepted by Canadian and American planes on Wednesday 
 
 Six Russian fighter jets were intercepted by American and Canadian planes off the coast of Alaska on Wednesday, US defence officials have confirmed. 
 
 They entered what is known as the Air Defence Identification Zone (ADIZ), but did not enter US air space. 
 
 The planes, two of which were MiG 31 jets, left the area without incident. 
 
 Officials said this type of incident was not uncommon, and happens up to 10 times a year. 
 
 The ADIZ is a zone of airspace which extends out approximately 200 miles from the coastline and is mainly within international airspace. 
 
 US sovereign air space extends 12 nautical miles from land. 
 
 Two Alaskan-based F-22 fighter jets and two Canadian CF-18 fighter jets were scrambled to intercept the Russian planes in two separate incidents on Wednesday evening and Thursday morning. 
 
 Also on Wednesday, the Swedish Foreign Ministry said two Russian military aircraft had crossed into Swedish air space south of the Baltic Sea island of Oland. 
 
 The ministry called it a "serious violation". 
 
 Sweden has said it has summoned the Russian ambassador over the incident. ||||| Story highlights U.S. official: Incident related to visit by Ukraine President 
 
 NORAD says six Russian aircraft flew about 55 nautical miles from Alaska coastline 
 
 Two Russian planes flew about 40 miles off Canadian coastline, NORAD says 
 
 (CNN) Two U.S. jets this week intercepted six Russian planes that neared U.S. airspace off Alaska and Canadian planes intercepted two Russian bombers that approached Canadian airspace, NORAD reported. 
 
 A U.S. official told CNN's Barbara Starr that officials in Washington think the incidents were related to the visit by Ukrainian President Petro Poroshenko, who talked to Canadian officials Wednesday and President Barack Obama on Thursday. The United States promised Ukraine $46 million in nonlethal aid for its battle with pro-Russian militants. 
 
 On Wednesday evening, two Alaskan-based F-22 fighter jets intercepted two Russian IL-78 refueling tankers, two Russian Mig-31 fighter jets and two Russian Bear long-range bombers, according to Capt. Jeff Davis of the North American Aerospace Defense Command (NORAD). 
 
 More than six hours later, early Thursday morning, two Canadian CF-18 fighter jets intercepted two Russian Bear long-range bombers in the Beaufort Sea, Davis said. Those Russian planes came within about 40 nautical miles of the Canadian coastline, he said. 
 
 Though the planes did not enter sovereign territory, the statement said, they did enter the U.S. Air Defense Identification Zone west of Alaska and the Canadian ADIZ, according to a statement. 
 
 Read More ||||| COLORADO SPRINGS, Colo. (AP) — Two F-22 fighter jets intercepted six Russian military airplanes that neared the western coast of Alaska, military officials said Friday. 
 
 Lt. Col. Michael Jazdyk, a spokesman for the North American Aerospace Defense Command, or NORAD, said the U.S. jets intercepted the planes about 55 nautical miles from the Alaskan coast at about 7 p.m. Pacific time Wednesday. 
 
 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 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.
– Russian military pilots seem to be getting a little adventurous these days. A pair of US military jets intercepted six Russian aircraft near the coast of Alaska Wednesday evening, reports AP. The Russian pilots never entered US airspace, but instead remained in something called the Air Defense Identification Zone, which extends about 200 miles from the coast. Still, NORAD sent up two US jets "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," says a spokesperson. The six Russian planes—two fighter jets, two long-range bombers, and two refueling tankers—eventually looped back toward Russia. Hours later, Canadian fighter jets intercepted two Russian long-range bombers over the Beaufort Sea, near the Canadian coast but again in the international zone. While such incidents aren't all that uncommon, one US official tells CNN that Moscow was likely expressing its displeasure about a visit by Ukraine President Petro Poroshenko to the US and Canada. Elsewhere, two Russian military aircraft entered Swedish air space without authorization, reports the BBC. Sweden's foreign ministry called it a "serious violation" and has summoned the Russian ambassador to complain. (Russia doesn't think Scotland's independence vote was up to snuff.)