Guided-missile destroyer USS Decatur (DDG-73) operates in the South China Sea on Oct. 13, 2016

A U.S. warship has conducted a freedom of navigation operation near Chinese holdings in the South China Sea, a U.S. defense official confirmed to USNI News.

USS Decatur (DDG-73) conducted the operation near Chinese holdings near Triton and Woody Islands in the Paracel Island chain off the coast of Vietnam in the South China Sea.

“USS Decatur (DDG-73) conducted this transit in a routine, lawful manner without ship escorts and without incident on Oct. 21… specifically in the vicinity of the Paracel Islands, to uphold the rights and freedoms of all States under international law, as reflected in the Law of the Sea Convention,” read a statement from Pentagon spokesman Cmdr. Gary Ross.
“The United States conducts these routine operations on a regular basis around the world, in full compliance with international law.”

The operation was first reported by newswire Reuters. Three Chinese ships shadowed Decatur, according to the wire.

The guided missile destroyer did not come within the 12 nautical mile territorial sea of either island but tested a claim that a baseline around the Paracels is Chinese territorial waters – a stance that is not recognized by international law.

“This transit appears to be an excellent challenge to China’s unlawful straight baselines around the Paracel Islands. There was no need in this case to transit within 12 nm of any individual island because China claims illegal straight baselines that encircle the entire island group,” James Kraska, a professor of international law, oceans law and policy at the U.S. Naval War College’s Stockton Center for the Study of International Law told USNI News on Friday.
“In the past the United States appeared to have challenged the straight baselines around the Paracel Islands with overflights only… The Decatur’s surface operations in this instance provides an unambiguous legal record that China’s purported straight baselines are not valid.”

Friday’s operation is the first freedom of navigation operation the U.S. has conducted in the South China Sea since May. Then USS William P. Lawrence (DDG-110) conducted a freedom of navigation operation past the Chinese installation on Fiery Cross Reef in the Spratly Island chain.

In January, USS Curtis Wilbur (DDG-54) came within 12 nautical miles of a Chinese installation on Triton Island. In late October in 2015, USS Lassen (DDG-84) conducted a FON op past the Chinese artificial holding on Subi Reef in the Spratlys.

Decatur is part of a San Diego-based surface action group that left in April made up of guided missiles destroyersUSS Spruance (DDG-111) and USSMomsen (DDG-92). Earlier this month the ship was operating with Bonhomme Richard Expeditionary Strike Group.