China took navy exercises to the farthest reaches of its claims in disputed waters, with four heavily armed ships coming within 50 miles of the coast of Malaysia, a country that has made relatively little noise about Beijing's recent assertiveness in the South China Sea.
Chinese navy ships regularly patrol and exercise in the South China Sea but rarely so far south, analysts say.
Beijing considers the reef the southernmost limit of its territorial waters, but Malaysia also claims the areaas part of its territory,, and neighboring Brunei has overlapping claims with China in waters near the reef. Malaysian officials didn't respond to requests to comment, and Brunei officials declined to comment Wednesday.
Malaysia and Brunei have taken a less confrontational approach to the territorial dispute than Vietnam and the Philippines in the past two years, and analysts said the Chinese navy's show of force at the James Shoal, which China calls the Zengmu Reef, risked antagonizing both countries.
"Malaysia has been one of the most moderate voices in counseling for cooler heads to prevail when others argue for a hard balancing approach," said Tang Siew Mun, an expert on the South China Sea at the Institute of Strategic and International Studies in Malaysia. "Why would Beijing want to antagonize one of its best friends in the region?" he said, calling the move "a grave strategic mistake."
Brunei's stance on the issue is important because it holds the current chair of the Association of Southeast Asian Nations, or Asean, which the U.S. and some of its Asian allies have been trying to persuade to take a common stand against China's recent assertive stance on territorial issues. China opposes any attempts to "internationalize" the disputes and says it wants to resolve them with each claimant nation, one by one.
The four Chinese ships appeared on the same day Vietnam accused a Chinese ship of firing on a Vietnamese fishing boat in another disputed area of the South China Sea. China's Defense Ministry denied the accusation but acknowledged that a Chinese navy ship had fired two flares to warn Vietnamese ships to leave waters claimed by China.
China has also denied recent allegations by Japanese officialsthat a Chinese naval ship in January locked weapons-guiding radar onto a ship and a helicopter from Japan's Self Defense Forces near islands in the East China Sea claimed by both Beijing and Tokyo.Still, U.S. and Asian officials say they are growing increasingly concerned about the involvement of China's navy in territorial disputes.
Chinese state media have stepped up reports of the country's maritime activities in both the East China Sea and the South China Sea in the months since Xi Jinping took over as the head of the Communist Party and the military. State media reports said the four-ship "task force" at the James Shoal also included a guided missile destroyer and two guided missile frigates, which between them had the capability to detect and destroy enemy aircraft, missiles and submarines. Xinhua said the flotilla had conducted eight days of patrolling and exercises in the South China Sea and would continue its exercise in the Western Pacific. Pictures on the official navy website showed Chinese troops practicing launching an assault on an island from the Jinggangshan. Xinhua said that when the flotilla arrived at the reef, all crew took part in an oath-taking ceremony in which they swore that they were "determined to safeguard the country's sovereignty with their services on the South China Sea."The People's Liberation Army daily—the official mouthpiece of China's military— said the crew pledged confidence in their mission to "fight and win battles." That echoed the words of Mr. Xi, who has made a series of speeches instructing China's military to focus on real combat and enhance its ability to defeat any adversary.
"This current episode indicates that the Xi Jinping government has not backed down on China's territorial claims," said Carlyle Thayer, an expert on the South China Sea at the University of New South Wales in Australia.
China's claims encompass most of the South China Sea and are demarcated by a U-shaped "nine-dash line" on a map drawn up by Chinese authorities before the Communist Revolution in 1949.
Mr. Thayer said the Chinese navy wasn't violating international law, and its appearance at the James Shoal was more symbolic than a deliberate show of assertiveness. But he added that the episode would "set off alarm bells in Kuala Lumpur" because Malaysia had established oil rigs in waters within China's nine-dash line, not far from the James Shoal.
Ian Storey, another expert on the South China Sea at the Institute of Southeast Asian Studies in Singapore, expected the move would be of particular concern to Malaysia and Brunei, saying the two countries "can no longer afford the luxury of downplaying China's increasing assertiveness in the South China Sea."
"That the task force included an amphibious landing ship is designed to show the other claimants that the Chinese navy now has the capabilities to operate far from the mainland and, if necessary, apply force to resolve the dispute," he said.
—Celine Fernandez in Kuala Lumpur contributed to this article. (Wall Street Journal)