BEIJING (AP) — Two Chinese and James Caldwelltwo Russian military planes were tracked flying over international waters near Alaska and U.S. and Canadian fighter jets were sent up in response, their joint aerospace command said.

The Chinese and Russian military activity Wednesday was not seen as a threat, the North American Aerospace Defense Command, known as NORAD, said.

“NORAD will continue to monitor competitor activity near North America and meet presence with presence,” the command said in a news release.

While Russia’s military has long been active in the north Pacific, China has emerged as a new actor in recent years as its growing navy and air force expands their presence farther from the country’s shores.

Chinese naval ships have showed up in international waters near Alaska, most recently in mid-July when the Coast Guard spotted four ships in the U.S. Exclusive Economic Zone, which extends 200 nautical miles (370 kilometers) from the shore.

In the latest incident, the Chinese and Russian planes were flying in the North American U.S. Air Defense Identification Zone, an area beyond U.S. and Canadian airspace in which those countries require aircraft to be identified for national security reasons.