A U.S. Arleigh Burke-class destroyer conducted a freedom of navigation operation, or FONOP, near one of China’s controversial artificial islands in the South China Sea on Thursday, according to U.S. defense officials.

Although tensions in the Pacific are high near the Korean peninsula, the South China Sea remains one of the most hotly contested regions of the world, with overlapping claims over the waterway levied by every nation that it touches, and one overarching claim bringing others into dispute championed by China.  China has been accused of militarizing the region, by way of an expanding the PLA Navy and more controversially, though installing military assets on contested naturally occurring islands, and controversial artificial ones.

The USS John S. McCain, named after both the grandfather and father of U.S. Senator John McCain who both achieved the rank of Admiral during their own naval careers, came to within 12 nautical miles of Mischief Reef in the Spratly Islands.  The island, which was nothing more than a reef before China’s effort to establish and militarize new islands in the waterway, is now the site of eight missile shelters, a large antennae array for communications and traffic monitoring, and a radar dome believed to be a part of a larger missile identification and defense system.

The United States has conducted a number of FONOP missions in the region in order to reaffirm the United States’ position that the military development of these islands, like China’s widespread claims of sovereignty, violate international law.  The United States has made it clear to China that its Navy will not acknowledge their aggressive claims, and operations like Thursday’s are intended to emphasize America’s commitment to keeping the waterway open for all law-abiding traffic.