WASHINGTON—A new Pentagon report says China’s reclamation of landmass among a string of artificial islands in the South China Sea has grown dramatically in recent months, and that Beijing is aggressively patrolling the waters there to assert its territorial claims.
The Pentagon report, issued late Thursday, said that, as of June, China has reclaimed 2,900 acres of landmass across a string of islands in the South China Sea known as the Spratlys, up nearly 50% from May, when the Pentagon said Beijing had claimed about 2,000 acres.
Washington fears that the islands will be used for military purposes and could create instability in one of the world’s biggest commercial shipping routes as China lays claim to what several other countries see as international waters. And, as China’s assertiveness grows, the risk of conflict with the U.S. and its allies grows along with it, defense officials have said.
The report comes about a month before a high-profile visit to Washington by Chinese President Xi Jinping, where the South China Sea issue, along with cybersecurity and monetary policy are likely to come up. Taken together, the issues portend a potentially difficult visit for Mr. Xi and for the Obama administration.
The rate of growth of the islands from China’s development activity has accelerated considerably, according to the report, which is titled “The Asia-Pacific Maritime Security Strategy” and was required by Congress in a 2015 defense bill.
The new Pentagon report reflects continuing U.S. skepticism of China’s claims earlier this month that it has halted its land reclamation activity. China said in early August that it had ceased reclamation operations, but U.S. officials questioned whether the actions had been stopped or would remain halted.
A spokesman for the Chinese embassy in Washington said late Thursday that China stopped reclamation in June. The spokesman, Zhu Haiquan, said that the facilities being built on the islands include those for the public good.
“China stands ready to open these facilities to other countries upon completion,” Mr. Zhu said. “We hope the U.S. side will view this in an objective and balanced way and respect regional countries’ efforts to maintain the peace and stability of the South China Sea.”
While not directly contradicting the Chinese claim, a Pentagon spokesman challenged Beijing late Thursday to elaborate on its plans.
“We encourage China to clarify whether this statement applies to all Chinese outposts in the Spratlys and Paracels, and whether China is permanently committing to stop further reclamation activities,” the spokesman said.
Before this year, defense officials estimated that Beijing had only reclaimed about 500 acres of landmass to build the artificial islands, mostly built atop of semi-submerged reefs by using dredged material from the seafloor.
The islands are big enough to erect buildings and house equipment, and, in one case, support a 3,000-foot runway.
Several of China’s neighbors make claims to the islands, including Brunei, Malaysia, the Philippines,Taiwan and Vietnam.
But China’s reclamation projects are far more aggressive than its neighbors’, the report says. In less than two years, China has reclaimed 17 times more land than any other claimant has in the past 40 years—accounting for about 95% of all reclaimed land in the Spratlys, according to the report.
Vietnam has reclaimed about 80 acres, Malaysia has reclaimed 70 acres, the Philippines has reclaimed 14 acres and Taiwan has reclaimed eight acres, the report says.
In May, The Wall Street Journal reported that U.S. surveillance confirmed the Chinese had placed two mobile artillery units on one of the artificial islands known as Johnson Reef.
Beijing says that construction of the islands, which sit about 700 miles off the Chinese coastline, is well within its rights as a sovereign nation. In a statement on Friday, China’s Foreign Ministry reiterated its position that the South China Sea isn’t a U.S.-China issue and that it “is resolving disputes with countries directly concerned through negotiation and consultation.”
The report indicated that at some sites, China has excavated deep channels and has built new berthing areas to allow access for larger ships that could be used to assert territorial claims.
“Though other claimants have reclaimed land on disputed features in the South China Sea, China’s latest efforts are substantively different from previous efforts both in scope and effect,” the report said. “The infrastructure China appears to be building would enable it to establish a more robust power projection presence into the South China Sea.”
Meanwhile, China is ramping up patrols of the area, taking “small, incremental steps” in the disputed areas that avoid military conflict, but work to “increase its effective control” over the islands, the report said. The report also cites expanded use of the Chinese Coast Guard, which Beijing is using to enforce its claims in both the East and South China Seas.
“China prefers to use its government-controlled, maritime law enforcement ships in these disputes, and operates [People’s Liberation Army Navy] vessels over the horizon so they are ready to respond to escalation,” the report says.
Although China isn't the only country to use nonmilitary assets to conduct “worrying or dangerous actions” against other countries in the region, China’s use of such vessels “has been, by far, the most active,” the report said.
Some U.S. military leaders have pushed the Pentagon to be more aggressive in countering China’s moves in the South China Sea, arguing for more assertive maritime and air patrols to fly within the 12 nautical mile territorial limit of some of the disputed islands that China claims. But some officials inside the Pentagon and at the White House say they have resisted flying such patrols for fear of provoking China.
Concerns linger that, if left unchecked, China’s claims to the islands could destabilize one of the world’s busiest commercial shipping routes.
On Thursday, Defense Secretary Ash Carter reiterated to reporters that the military would fly and steam where and when it wanted. But it remains unclear if the U.S. has ever actually flown or navigated to within the 12-nautical mile zone of those islands, which would likely result in a response from Beijing.
“The United States will continue to fly, sail and operate wherever international law permits,” Mr. Carter said. “As we’ve always the right to do, we will continue to do that, and none of this is going to change our conduct in any way.”