The two American warships involved on Sunday were carrying out maneuvers known as “freedom of navigation operations.” The operations, which the Obama administration curtailed somewhat but which picked up again under President Trump, are intended to exercise what the United States says are its rights under international law.
The two ships passed within 12 miles of four islands — Tree, Lincoln, Triton and Woody — according to an American defense official.
A spokesman for the United States Seventh Fleet, Cmdr. Clay Doss, did not discuss the details of the Chinese challenge but said that in 2017, American warships conducted similar operations in the waters of 22 different countries, including allies of the United States.
The operations “are not about any one country,” he said in a statement, “nor are they about making political statements.”
China, whose claims on the islands in the Paracel and Spratly Islands are not recognized, argues that passage within 12 nautical miles constitutes a violation of the country’s territory under the United Nations Convention on the Law of the Sea. In April, Chinese ships and aircraft challenged three vessels of the Australian Navy as they traveled to port calls in Vietnam.
“The United States naval vessels Antietam and Higgins entered without Chinese government permission into territorial waters” around the islands, which China calls the Xisha Islands, Colonel Wu said in the statement.
China’s military, he said, would be “firm and unwavering in its determination to strengthen sea and air operational preparedness construction” on the islands.