China late Thursday expressed its "strong dissatisfaction" with the U.S. over the Navy's latest freedom-of-navigation operation in which a warship sailed past one of China's man-made islands in the strategic South China Sea.
A leading U.S. think tank, meanwhile, released a new report documenting what it said was continuing reclamation work on Chinese-controlled islands in the area despite a recent claim by China's foreign minister that such work had stopped two years ago.
Foreign Ministry spokesman Geng Shuang said in a statement late Thursday that the U.S. move "severely undermines China's sovereignty and security, and severely endangers the safety of frontline personnel of both sides."
China, which claims virtually the entire South China Sea, routinely protests such operations, which President Trump's administration has continued partly to reassure allies locked in territorial disputes with Beijing.
"China has the firm determination to safeguard its territorial sovereignty and maritime interests," Geng said. The U.S. move will "compel China to take measures to further raise its capacity to defend national territory," he said.
A U.S. Navy official told the Associated Press that the destroyer John S. McCain sailed past Mischief Reef on Thursday. U.S. officials say the military will continue to sail, fly and operate wherever permitted by international law.
Geng said the Chinese navy "identified the U.S. warship, warned and expelled it."
China and the U.S. maintain different interpretations on international law as applied to the operation of warships, and Beijing has ignored a Hague arbitration court's ruling that invalidated much of its South China Sea claim.
Although the Philippines has taken steps to improve ties with China under its current leader, Rodrigo Duterte, presidential spokesman Ernesto Abella said Friday "we don't find [the sail-by] objectionable."
Tensions escalated after China began to build seven reefs, including Mischief, into islands, including three with runways, which the U.S. and China's neighbors fear could be used to project Beijing's military might and potentially obstruct freedom of navigation.
Firing back at criticism of China's activities, Foreign Minister Wang Yi said Monday that China had "stopped or already completed land reclamation" on its holdings in the South China Sea two years ago.
However, the Washington-based Center for Strategic and International Studies said China was continuing to reclaim land in the Paracel Islands to the north of the Spratlys.
Wang's claim "is false" and China's reclamation work "did not end in mid-2015 with the completion of its artificial islands in the Spratlys," said the report.
The Paracels play "a key role in China's goal of establishing surveillance and power projection capabilities throughout the South China Sea," the report said. "To this end, Beijing has undertaken substantial upgrades of its military infrastructure in the Paracels."
China occupies 20 outposts in the chain and improvements include the addition of harbors, helipads, an airstrip, hangars and a surface-to-air missile battery, the report said.
Earlier, Wang said talks on a nonaggression pact aimed at preventing clashes from erupting in the South China Sea may start this year if "outside parties" don't cause a major disruption, in an apparent reference to Washington and allies such as Japan.
The U.S. is not a party to the disputes in the busy and potentially oil- and gas-rich waters that also involve Brunei, Malaysia, the Philippines, Taiwan and Vietnam. Washington, however, has declared it in its interest to ensure that the conflicts are resolved peacefully and that freedom of navigation and overflight remain unhampered. An estimated $5 trillion in annual trade passes through the waterway.
Washington's actions came as it courts the help of China, North Korea's ally, in taming Pyongyang's nuclear weapons ambitions and ending its missile tests.
5:15 a.m.: This article was updated with information from a report by the Center for Strategic and International Studies.