Russian fighter jets invade airspace over Alaska. Two Russian aircraft have entered an air defense zone outside Alaska airspace.

It was the second time this week that such an incident has occurred. Four Russian aircraft had already entered the ADIZ on Tuesday, prompting NORAD, a joint US-Canada air surveillance and air defense facility, to issue a similar statement. “These Russian activities in the Alaska ADIZ occur regularly and are not considered a threat,” NORAD said Friday. It is unclear why the Russian military aircraft could have flown in Alaska's ADIZ, reports the news portal Newsweek.