At about 1:30 am Thursday, two Canadian CF-18 fighter jets intercepted two of the long-range bombers about 64 nautical kilometres off the Canadian coastline in the Beaufort Sea.
Lt Col Michael Jazdyk, a spokesman for the North American Aerospace Defense Command, or NORAD, said the US jets intercepted the planes about 88 kilometres from the Alaskan coast at about 7 pm Pacific time Wednesday.
The Russian planes were identified as two IL-78 refuelling tankers, two Mig-31 fighter jets and two Bear long-range bombers. They looped south and returned to their base in Russia after the US jets were scrambled.
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 bi-national American and Canadian command responsible for air defense in North America.