The US Coast Guard encountered a Russian ship near the Aleutian Islands last week, less than a month after Chinese military ships in the region.

The Coast Guard said Friday that the cutter Alex Haley identified a Russian Vishnya-class warship on August 5. The Soviet-era ships were built for intelligence gathering but are equipped with weapons such as surface-to-air missile launchers.

The Coast Guard said it spotted the Russian vessel near Atka Island in the central Aleutian Islands. It was in the U.S. exclusive economic zone, a large area that stretches 200 nautical miles off the U.S. coast. The zone is considered international waters, but the U.S. maintains control over resources in the region.

The Alex Haley, one of the Coast Guard’s larger cutters and homeported in Kodiak, followed the Russian vessel as it passed through the region but did not communicate with it.

Haley’s senior officer, Commander Steven Baldovsky, said the crew “took all necessary steps to ensure there was no disruption to U.S. interests.”

Both the Russian and Chinese navies have been regularly present in the Aleutian Islands in recent years, and the Pentagon raises alarm over increased cooperation between both countries in the Arctic.