The USS Stethem, an Arleigh Burke-class destroyer, arrives at the Joint Civil-Military Complex on South Korea’s Jeju Island. (U.S. Navy/Mass Communication Specialist 1st Class Ty C. Connors)

An American guided-missile destroyer sailed near a disputed island in the South China Sea on Sunday, a U.S. defense official said, marking the second such operation since President Trump took office.

The Japan-based USS Stethem, an Arleigh Burke-class destroyer, sailed within 12 miles of Triton Island, a small landmass in the Paracel Islands chain. Fox News first reported on the incident, known as a freedom-of-navigation operation, or FONOP.

Triton Island is claimed by China, Vietnam and Taiwan. In May, a U.S. destroyer sailed well within 12 miles of Mischief Reef, a man-made island in the Spratly Islands to the south of the Paracels. During Sunday’s operation, a Chinese warship tailed the USS Stethem, Fox News reported, although it is unclear how close the ship came to the American vessel.

The 12-mile line is the internationally recognized distance that separates the shores of a sovereign nation from international waters. The United States has routinely conducted voyages within this 12-mile limit around islands in the South China Sea as a message to countries such as China, Taiwan, Vietnam and the Philippines. Many of these nations have laid claim to islands in the South China Sea, some of which are no more than tiny strips of sand and reef. The last time the U.S. Navy sailed near Triton Island was in January 2016, when the USS Curtis Wilbur came within 12 miles of its shores. The Pentagon did not notify any of the island’s claimants before that operation.

Capt. Charlie Brown, a spokesman for the U.S. Navy Pacific Fleet, did not confirm the Sunday operation but said in an emailed statement that the Navy routinely conducts FONOPs and that the operations are not “about any one country, nor are they about making political statements.”

“U.S. forces operate in the Indo-Asia-Pacific region on a daily basis, including in the South China Sea,” Brown said. “All operations are conducted in accordance with international law and demonstrate that the United States will fly, sail, and operate wherever international law allows. That is true in the South China Sea as in other places around the globe.”

In the Paracels and Spratlys, China has built up a number of small islands into fully functional military facilities complete with airfields and antiaircraft defenses. The White House, in both the Obama and Trump administrations, has seen the militarization of the South China Sea as a threat to stability in the resource-rich region, where ships from numerous countries have long fished.