BRP SIERRA MADRE, a marooned transport ship which Philippine Marines live in as a military outpost, sits on the disputed Second Thomas Shoal, part of the Spratly Islands in the South China Sea. — REUTERS

THE PHILIPPINES is prepared to respond to China’s attempts to foil its resupply missions in the South China Sea, a top security official said on Wednesday, adding that the operations would be adjusted to counter Beijing’s conduct in the waterway.

Jonathan Malaya, the spokesman of the National Security Council, said the Philippines would keep its position at Second Thomas Shoal and there would be no letup in resupply missions to a handful of Filipino soldiers stationed on a grounded warship there.

“Our commitment to maintain BRP Sierra Madre will always be there, so any attempt by China to interfere with resupply missions will be met by the Philippines in a fashion that protects our troops,” he told a maritime forum.

Mr. Malaya reiterated that the countermeasures announced by Philippine President Ferdinand R. Marcos, Jr. last week against “aggressive” actions by China’s coast guard would be “multi-dimensional” and not solely military in nature.

These measures include making “changes and adjustments” to Philippine resupply missions and operations in the South China Sea, he said without elaborating, citing security concerns.

Echoing an earlier call by the Philippine Defense secretary for the public not to fall victim to Chinese propaganda, Mr. Malaya warned of “foreign malign influence” meant to weaken the Philippines.

“We have seen that they are working here through their surrogates or if we may call them amplifiers, because there are definitely Chinese narratives which run counter to the truth,” he added.

The Chinese Embassy in Manila did not immediately reply to a request for comment.

The Philippines and China have had a series of maritime run-ins, including water cannon use and heated verbal exchanges that has triggered concern about an escalation at sea.

China claims almost the entire South China Sea as its territory, policed by an armada of coastguard vessels, some more than 1,000 km (620 miles) from its mainland. China has maintained its responses have been appropriate in the face of Philippine encroachment.

In 2016, the Permanent Court of Arbitration in the Hague said China’s claims in the South China Sea had no legal basis, a decision Beijing has rejected.

The row comes at a time when the Philippines and United States are deepening military ties, frustrating China, which sees Washington as interfering in its back yard.

Mr. Marcos will meet his American and Japanese counterparts at a three-way summit in Washington on April 11, and Mr. Malaya said a “big aspect” of their discussions would be on security.

Also on Wednesday, a special Senate committee approved a bill that seeks to set up naval outposts in the South China Sea to assert Philippine sovereignty.

Under Senate Bill No. 654, the country will set up forward operating bases — small-scale naval and military facilities that can serve as potential sites for future upgrade and expansion “for national security purposes.”

It allots P1 billion for 12 possible outposts including in Busuanga in Palawan province, Subic Bay in Zambales and Mavulis Island in Batanes. At Wednesday’s hearing, the Philippine Navy sought 13 more bases to be built in the South China Sea.

The Senate special committee on Philippine Maritime and Admiralty Zones switched to a closed-door hearing to discuss the reason for the Navy’s proposal.

Meanwhile, Senator Ana Theresia N. Hontiveros-Baraquel on April 2 filed a resolution seeking to investigate the so-called gentleman’s agreement with China under ex-President Rodrigo R. Duterte to keep the status quo at Second Thomas Shoal, including barring repairs to BRP Sierra Madre.

The agreement is “tantamount to a surrender of the Philippines’ sovereignty and an act of treason,” she said in Senate Resolution No. 982.

Ex- presidential spokesman Herminio L. Roque earlier said Mr. Duterte had made deal with China not to bring building and repair materials to troops stationed at the World War II-era ship at Second Thomas Shoal.

“While China, in any case, will most likely attack our resupply missions en route to Ayungin (Second Thomas Shoal), this sham of an agreement only gave Beijing more ammunition to assert her baseless claims,” she said in a statement.

China’s Foreign Ministry earlier said a March 23 Philippine resupply mission had tried to transport building materials to the grounded ship.

The Senate resolution called on Mr. Roque to give more details of the deal and how it was brokered.

Ms. Hontiveros-Baraquel has said the deal was not surprising given Mr. Duterte’s foreign policy pivot to China.

“Whatever foreign policy direction former President Rodrigo R. Duterte took in his administration is his exclusive prerogative as chief architect of foreign policy,” Mr. Roque said in a statement in response to the proposed probe.

He said describing the deal as “treasonous” showed the senator’s “obvious gross ignorance of the law.” Mr. Roque had said the deal would not bind the Marcos government because it is not a treaty. — John Victor D. Ordoñez with Reuters