WASHINGTON

A Chinese and Russian flight near Alaskan airspace was the "first time" the US detected a joint flight between the two countries, the head of the Pentagon said Thursday.

"I won't discuss any intelligence issues here at the podium, but again, this first time that we've seen these two countries fly together like that. They didn't enter our airspace," Lloyd Austin told reporters alongside Gen. CQ Brown, chairman of the joint chiefs of staff.

His remarks came one day after North American Aerospace Defense Command (NORAD) said American and Canadian warplanes intercepted two Russian and two Chinese bombers in international airspace near the state of Alaska.

"This was not a surprise to us. We closely monitored these aircraft, tracked the aircraft, intercepted the aircraft," Austin said, adding that the US has "very good" surveillance capabilities.

The defense chief said Chinese and Russian were at the "closest approach" about 200 miles off the American coast.

"In terms of the relationship between Russia and China, this is a relationship that we have been concerned about, mostly because we're concerned about China providing support to Russia's illegal and unnecessary war in Ukraine," Austin added.

NORAD said Wednesday that the activity in the Alaska Air Defense Identification Zone (ADIZ) was "not seen as a threat," and it will continue to monitor competitor activity near North America.