The US Navy said that one of its destroyers had sailed close to the Chinese-controlled Paracel Islands in the South China Sea on Friday, asserting international freedom of navigation rights in the contested waters.
The USS Wayne E. Meyer guided-missile destroyer passed through the area of the Paracels east of Vietnam and South of China's Hainan Island without requesting permission from Beijing, or from Hanoi or Taipei, which also claim ownership of the archipelago.
The move could add to the tensions between the US and China, now bogged down in a grinding trade war, as Beijing pushes to expand its military reach globally.
"USS Wayne E. Meyer challenged the restrictions on innocent passage imposed by China, Taiwan, and Vietnam and also contested China's claim to straight baselines enclosing the Paracel Islands," said Commander Reann Mommsen, spokesperson for the US 7th Fleet based in Japan.
"With these baselines, China has attempted to claim more internal waters, territorial sea, exclusive economic zone, and continental shelf than it is entitled under international law."
China has laid claim to nearly all of the South China Sea and has built numerous military outposts on the small islands and atolls of the region, angering other claimants Vietnam, the Philippines, Malaysia, Brunei and Taiwan.
In recent months, the US military has stepped up its "freedom of navigation operations" or "FONOPS" in the region, irking Beijing but not sparking any direct confrontation thus far.
China has effectively drawn a property line around the whole of the Paracels archipelago -- which it calls the Xisha Islands -- to claim the entire territory.
But the United States says that does not accord with international law on archipelagos and territorial seas.
The FONOPS "demonstrate that the United States will fly, sail, and operate wherever international law allows -- regardless of the location of excessive maritime claims and regardless of current events," Mommsen said.