DAVAO CITY—President Rodrigo Duterte on Sunday said he would not stop China from building on a disputed shoal near the Philippine west coast because it was too powerful.

Mr. Duterte made the statement in reaction to reports that China would set up an environmental monitoring station on Panatag Shoal (international name: Scarborough Shoal) off the coast of Zambales province.

“We cannot stop China from doing those things. Even the Americans could not stop them,” he said during a press conference here shortly before flying for his state visit to Burma (Myanmar).

“What do you want me to do? Declare war against China? I can’t. We will lose all our military and policemen tomorrow and we [will be] a destroyed nation,” he told a press conference before departing for a visit to Burma.

Mr. Duterte said he would tell the Chinese: “Just keep it (the waters) open and do not interfere with our Coast Guard.”

Benham Rise

He also brushed aside concerns over Chinese survey ships that had been seen near Benham Rise—waters east of the main island of Luzon that have been recognized by the United Nations as indisputably Philippine territory.

Earlier this month, Defense Secretary Delfin Lorenzana said he was very concerned that the Chinese ships had been seen at that location, sometimes for as long as a month.

But Mr. Duterte said: “So what if they stop there? They admit it is within the territory of the Philippines. That does not satisfy you?”

He described the complaints against China as “nit-picking.”

Mr. Duterte’s predecessor, Benigno Aquino III, had actively challenged China’s claim to control most of the South China Sea, despite counterclaims by several other nations.

But Mr. Duterte, who took office last year, has reversed that policy and was seeking billions of dollars worth of investments and grants from Beijing.

“We are now improving the economy because of the help of China. Why will you be so shameless just because they are passing by?” he told reporters on Sunday.

Beijing has already reclaimed large areas around several islets and reefs in the Spratly archipelago and elsewhere in the South China Sea, and installed military facilities on some of them.

Warning by analysts

However, analysts warned that China’s building on Panatag Shoal would radically change the situation since it is just 230 kilometers (143 miles) from Luzon.

Outposts on the shoal would put Chinese jet fighters and missiles within easy striking distance of military bases in the Philippines, some of which could host US troops.

The shoal also commands the northeast exit of the sea, so a Chinese military outpost there could stop other countries’ navies from using the waters.

In this Monday, March 13, 2017 file photo, Philippine President Rodrigo Duterte reacts during a press conference at the Malacanang presidential palace in Manila, Philippines. Duterte says his militarily inferior country can't stop China's actions in contested waters, responding to a reported plan by Beijing to construct an environmental monitoring station in a disputed shoal off the Philippines' northwest coast. Duterte, however, warned Sunday, March 19, that he would invoke a July 12 arbitration ruling that invalidated China's territorial claims in the South China Sea if the Chinese "start to tinker with the entitlement," apparently meaning when Beijing starts to tap the offshore area's resources.

China seized the strategic shoal, which is also claimed by the Philippines, in 2012, and Washington has warned Beijing against carrying out the same land reclamation work there that it has done in other parts of the South China Sea.

Monitoring stations

Xiao Jie, the mayor of what Beijing calls Sansha City, an administrative base for disputed South China Sea islands and reefs it controls, said China planned preparatory work this year to build environmental monitoring stations on a number of islands, including Scarborough Shoal.

The monitoring stations, along with docks and other infrastructure, form part of island restoration and erosion prevention efforts planned for 2017, Xiao told the official Hainan Daily.

The report comes ahead of a visit to Beijing at the weekend by US Secretary of State Rex Tillerson, where he was expected to reiterate US concern about Chinese island building.

Tillerson has called the activity “illegal” and last June, then US Defense Secretary Ash Carter warned that any move by China to reclaim land at Scarborough Shoal would “result in actions being taken by the both United States and … by others in the region which would have the effect of not only increasing tensions, but isolating China.” —WITH A REPORT FROM THE WIRES000