HONG KONG — China may be building a series of radar facilities on artificial islands in disputed waters in the South China Sea, which would help it to establish “effective control” over sea and air in one of the world’s busiest waterways, according to a report issued this week.
The report, released on Monday by the Center for Strategic and International Studies in Washington and based on satellite images taken as recently as Feb. 12, came less than a week after the United States said that China appeared to have deployed surface-to-air missiles on another disputed island.
Late Tuesday, the Pentagon said recent deployments of fighter jets to that island put China at odds with its neighbors in the region, including Vietnam and the Philippines.
The possible radar facilities are far to the south of the missile batteries, on a series of artificial islands in the Spratly chain, closer to the shores of Vietnam, the Philippines and the island of Borneo than to China. In September, China’s president, Xi Jinping, speaking with President Obama at the White House, said that Beijing “does not intend to pursue militarization” in the Spratlys, or the Nansha, as the islands are known in China.
Last week, Wang Yi, the foreign minister of China, said that the country’s artificial islands in the South China Sea were being used for civilian purposes, pointing out that Beijing had built lighthouses and weather observation facilities there.
But experts say the satellite imagery tells another story.
One structure, built on a newly constructed island on Cuarteron Reef, more than 600 miles south of the southernmost Chinese province, appears to be a high-frequency radar center, made up of a series of tall poles laid out on a flat, rectangular surface, according to the report, compiled by the Asia Maritime Transparency Initiative at C.S.I.S.
Such radar is used to detect ship traffic and measure ocean currents, and it can also track aircraft. Other likely radar sites, some that might have gun emplacements, are on Gaven Reef, Hughes Reef and Johnson South Reef in the Spratlys, the report said.
“Most people in this area recognize that the facilities that China has constructed are primarily for strategic reasons. They’re for military purposes, rather than civilian,” said Ian Storey, a senior fellow at the Institute of Southeast Asian Studies in Singapore. “But that’s how China will spin it.”
Hua Chunying, a spokeswoman for the Chinese Foreign Ministry, told reporters in Beijing on Tuesday that she was unaware of the details of the report about possible radar facilities. But she reiterated Mr. Wang’s assertion that construction in the Spratlys was focused on “public goods,” urging journalists not to focus on military issues.
She left no doubt that China believed it had every right to do what it wanted on the artificial islands, saying its claim over the South China Sea islands was “indisputable.”
“China’s deployment of limited, necessary defense facilities on its own territory is its exercise of its right of self-defense to which a sovereign state is entitled under international law,” Ms. Hua said.
Separately, on Tuesday Fox News, citing two United States officials it did not name, reported that China had in recent days sent fighter jets to Woody Island, an island in the northern part of the South China Sea where this month it had deployed surface-to-air missile batteries.
China has deployed military aircraft to the island before, but Tuesday’s report came as China’s foreign minister, Wang Yi, was in Washington to meet with Secretary of State John F. Kerry and a week after leaders of Southeast Asian nations met with President Obama at the Sunnylands ranch in California, where Mr. Obama discussed the need to halt further militarization and land reclamation in the sea.
China’s claims in the South China Sea are far more expansive than those of other nations in the region, demarcated on the country’s maps by a nine-dash line — likened by some officials to a cow’s tongue — that extends more than 900 miles south of the Chinese island province of Hainan and encompasses nearly the entire sea. In a separate report last month, C.S.I.S. said that the Chinese military buildup in the region meant that the South China Sea “will be virtually a Chinese lake” by 2030.
“Improved radar coverage is an important piece of the puzzle — along with improved air defenses and greater reach for Chinese aircraft — toward China’s goals of establishing effective control over the sea and airspace throughout the nine-dash line,” the report issued this week said.
China has embarked on an island-building campaign under Mr. Xi, who came to power in late 2012. In the past 19 months, China has constructed more than 3,000 acres of artificial land on the reefs and shoals in the shallow sea, according to American officials, prompting protests from neighbors and increasing tensions with the United States, which counters China’s claims with patrols by ships and aircraft.
Ms. Hua accused the Americans of asserting their own domination with those patrols, which American officials said were intended to demonstrate freedom of navigation in international waters. “The U.S. side has been talking about freedom of navigation, but in their minds I’m afraid they are thinking about absolute maritime hegemony,” she said.