Fighter jets from Canada and the United States intercepted Chinese and Russian bombers off the coast of Alaska, the North American Aerospace Defense Command announced Wednesday.

NORAD said it detected and tracked two Russian TU-95 and two Chinese H-6 military aircraft that were operating in the Alaska Air Defense Identification Zone. An Air Defense Identification Zone “begins where sovereign airspace ends,” according to NORAD. The zone is an area of international airspace “that requires the ready identification of all aircraft in the interest of national security,” according to the command.

The command said the Russian and Chinese bombers did not enter the sovereign airspace of the U.S. or Canada. It also said the activity in the zone Wednesday was not seen as a threat.

Defense Secretary Lloyd Austin told reporters Thursday that the closest point of approach by the bombers was 200 miles off the Alaskan coast.

Austin, at a press briefing, said this was the first time U.S. officials have seen Russia and China fly together, but it did not come as a surprise. 

“We closely monitored these aircraft, tracked the aircraft, intercepted the aircraft, which demonstrates that our forces are at the ready all the time and we have very good surveillance capabilities,” Austin said.

NORAD previously said in May it was tracking four Russian military aircraft operating in the Alaska ADIZ. At the time, NORAD said the activity “occurs regularly and is not seen as a threat.”

When it comes to the relationship between Russia and China, Austin said it’s a concern and the Department of Defense will monitor how it continues to develop.

“We will remain focused on protecting the homeland here,” Austin said.

NewsNation digital producer Cassie Buchman contributed to this report.