MANILA, Philippines — Philippine President Rodrigo Duterte stopped construction work on a newly formed sandbar in the disputed South China Sea after China protested, the defense chief said Wednesday, disclosing details of the territorial spat for the first time.

The dispute over a string of sandbars called Sandy Cay emerged in August and prompted China and the Philippines to consider negotiating some sort of arrangement to prevent such incidents from spiraling out of control, Lorenzana said.

The rift over the tiny sandbar, where Filipinos planned to erect fishermen’s shelters, in the group near Philippine-occupied Thitu island in the Spratlys archipelago remains unresolved but both sides pledged not to occupy any new territory, he said.

China’s claims to most of the South China Sea overlap those of the Philippines and four other governments. Despite that, tensions have eased since Duterte took over as president last year and took steps to thaw once-frosty relations with Beijing.

Duterte has courted Chinese trade and assistance and taken a nonconfrontational approach to their territorial disputes. He has refused to immediately take up with China a ruling by a U.N.-linked tribunal that invalidated Beijing’s sprawling claims in the South China Sea, sparking criticism from nationalists and left-wing groups, which wanted him to demand immediate Chinese compliance with the landmark decision.

“We tried to put some structures in one of the sandbars near our island and the Chinese reacted,” Lorenzana told a diplomatic and security forum in Manila, adding that Duterte later ordered, “Let’s pull out.”

Duterte made the decision after Foreign Secretary Alan Peter Cayetano advised him of an agreement involving China and the Philippines for a halt on new construction in the disputed waters, Lorenzana later told a news conference.

“We brought up people there to occupy, to put up structures for our fishermen,” Lorenzana said. He said the Chinese “complained that we are occupying a new feature.”

Philippine foreign affairs and military officials refused to divulge details of the dispute at Sandy Cay in August.

A government security report seen by the AP in August said three Chinese navy ships, a Chinese coast guard ship and 10 Chinese fishing vessels took positions off Sandy Cay after spotting the Filipinos on the barren sandbar. The nearest sandbar in Sandy Cay is about 2.5 nautical miles (4.6 kilometers) from Philippine-occupied Thitu Island.

On Aug. 15, a blue Chinese helicopter flew low off Thitu’s southwest coast, the report said.

The Chinese military presence off Sandy Cay sparked concerns in Manila.

Philippine Supreme Court Senior Associate Justice Antonio Carpio, who has studied the disputes extensively, said then that the Chinese navy ships and other vessels encroached in the Philippine island’s 12-nautical mile (22-kilometer) territorial waters. “In short, Sandy Cay is a Philippine land territory that is being seized, to put it mildly, or being invaded, to put it frankly, by China,” Carpio said.

The long-unresolved disputes are among issues expected to get the spotlight at an annual summit of Southeast Asian nations and their Asian and Western counterparts in Manila next week.

China and the Association of Southeast Asian Nations, which includes four governments involved in the sea feud, agreed earlier this year on a framework for a long-proposed nonaggression pact in the disputed waters. The framework is to serve as a roadmap for negotiations on a so-called code of conduct in the often-volatile waterway.

ASEAN, currently led by the Philippines, has come under criticism for failing to take more effective steps to rein in aggressive behavior in the disputed waters, including China’s transformation of seven disputed reefs into islands with landfill. Many of the 10-nation bloc’s members depend largely on China for trade, investment and aid.

“If ASEAN pursues an over-abundance of caution, it risks becoming only a bystander to the events within its own region,” former Philippine Foreign Secretary Albert del Rosario told the Manila forum Wednesday.