The North American Aerospace Defence Command, which detected the aircraft as they approached Alaska, painted the incident as a normal occurrence that did not pose any threat.

The North American Aerospace Defence Command (NORAD) says two F-22 and two CF-18 fighter jets identified two Russian Tu-160 Blackjack strategic bombers that were entering an area patrolled by the Royal Canadian Air Force on Saturday morning.

"We haven't seen this level of activity since July 2015."