The four Chinese warships came within 46 miles of Alaska’s coast.

During a routine patrol near Alaska’s Aleutian Islands on Aug. 30, U.S. Coast Guard vessels spotted four Chinese warships conducting military and surveillance operations.

The ships from the People’s Liberation Army Navy ventured as close as 46 miles to the Aleutian Islands, the Coast Guard said on Monday.

The patrol consisted of the U.S. Coast Guard Cutters Bertholf and Kimball, both Legend-class maritime security cutters.

The Chinese ships were in the U.S. exclusive economic zone, which stretches about 200 miles from Alaska’s coast, from Aug. 29 to Sept. 1. They did not enter U.S. territorial waters, which extend 12 miles from the shore. Read more at ArcticToday.