China’s Coast Guard claimed it entered waters of the Arctic Ocean for the first time as part of a joint patrol with Russia – in the latest sign of enhanced coordination between the two in a region where Beijing has long wished to expand its footprint.

China said its Coast Guard vessels entered the Arctic Ocean for the first time, patroling the waters jointly with Russian ships on a mission that underscored the growing cooperation between Beijing and Moscow in the region.

The U.S. Coast Guard said Tuesday that it spotted two Russian ships and two Chinese vessels passing through the Bering Sea in formation on Saturday, in a sign of the growing cooperation between Beijing and Moscow in the Arctic.