The disputes between China and four of its Southeast Asian neighbors over claims in the South China Sea have become so intense, the prospect of open conflict is becoming more likely, an authoritative new report says.
The disputes, enmeshed in the competition for energy resources, have reached an impasse, according to the report, by the International Crisis Group, a research organization that has become a leading authority on the frictions.
“All of the trends are in the wrong direction, and prospects of resolution are diminishing,” said the report, titled “Stirring Up the South China Sea: Regional Responses.”
The pessimistic conclusion came a day after China stepped up its political and military control of the Paracel and Spratly Islands, which both Vietnam and the Philippines claim, and the Macclesfield Bank, claimed by the Philippines. The islands are known in Chinese as Xisha, Nansha and Zhongsha.
On Monday, the Philippine president, Benigno S. Aquino III, announced plans to buy aircraft, including attack helicopters, that could be used in territorial disputes in the South China Sea. China and the Philippines have competing claims there over the Scarborough Shoal and potentially energy-rich underwater ground around Reed Bank, among other areas.
In a speech before a joint session of the Philippine Congress, Mr. Aquino adopted an aggressive stance against an unspecified threat. “If someone enters your yard and told you he owns it, will you allow that?” he said. “It’s not right to give away what is rightfully ours.”
The Chinese Foreign Ministry responded on Tuesday, saying that the Philippine president had no legal standing to rely on the United Nations Convention on the Law of the Sea as the basis for his claim on Huangyan Island, the Chinese name for the Scarborough Shoal.
The analysis by the International Crisis Group apportions blame to both China and its neighbors for the ratcheting up of incidents and tensions in the sea, one of the most traveled bodies of water in the world and a vital strategic pathway for the United States and its allies. The group’s Beijing office has spent two years studying the South China Sea, interviewing decision makers in China and in the claimant countries.
In April, the group released a report focused on the military and civilian agencies that play a role in China’s actions in the South China Sea, ranging from the People’s Liberation Army to a fisheries bureau.
The vagueness of China’s claims to islands and energy resources in the sea has rattled other claimants, the new report said. China bases some of its claims in the sea on discoveries by ancient Chinese navigators. More specifically, China lays claim to everything within what is called a nine-dash map drawn shortly after World War II. By some estimates, the nine dashes incorporate 80 percent of the South China Sea.
But China’s assertive approach has been matched by Vietnam and the Philippines, which are forcefully defending their claims and enlisting outside allies, the report said.
“South China Sea claimants are all anxious to pursue oil and gas exploration in the portions of the sea that they claim, and are concerned with protecting their claimed fishing grounds as coastal waters become depleted,” it said. The fact that the waters are mostly patrolled by civilian vessels run by national governments was of little comfort.
“In spite of being more lightly armed and less threatening than navy ships, civilian law enforcement vessels are easier to deploy, operate under looser chains of command and engage more readily in skirmishes,” the report said.
In an example of civilian vessels’ plying the South China Sea with possibly serious consequences, the Philippine Foreign Ministry said on Tuesday that it objected to a fleet of 29 fishing vessels, a cargo vessel and three other ships, protected by a Chinese Navy vessel near Fiery Cross Reef and Subi Reef, two areas of the South China Sea that the Philippines claims.