Senate President Pro Tempore Panfilo “Ping” Lacson on Saturday pushed back against proposals to give up the Kalayaan Island Group (KIG), warning that abandoning the disputed territory would be no different from surrendering Luzon — or the entire Philippines.

The former police chief anchored his position on the legal doctrine of res nullius or terra nullius, which recognizes ownership through first discovery and occupation. He noted that Filipino adventurer Tomas Cloma discovered and occupied the Spratlys before turning them over to the Philippine government.

“Even non-lawyers were taught this in school,” Lacson said.

“Giving up the Kalayaan Island Group is no different from giving up Luzon Island or the entire country,” Lacson added, “It is ours under international law.”

His remarks followed a statement by Sen. Rodante Marcoleta during a Commission on Appointments hearing, suggesting the Philippines should consider relinquishing the KIG because some of its features lie “way beyond” the country’s exclusive economic zone (EEZ).

“I cannot let that pass,” Lacson said in a radio interview. “I cannot accept that.”

Lacson stressed that the issue is not merely theoretical or legal. Kalayaan is a municipality of Palawan, home to about 300 Filipino families, with Pag-asa Island serving as the country’s civilian and military foothold in the West Philippine Sea.

“There were Filipinos living on Pag-asa Island,” Lacson said.

Emboldening China

Maritime law expert Atty. Jay Batongbacal, director of the UP Institute for Maritime Affairs and Law of the Sea, warned that such statements could weaken the Philippines’ legal and diplomatic position and embolden China.

“It is unacceptable for a senator of the republic to suggest giving up any portion of national territory on his own say-so,” Batongbacal said, adding that sovereignty issues require diplomacy and decision-making at the highest level, with public consent.

Batongbacal said Marcoleta’s remarks reflected a misunderstanding of international law, emphasizing that maritime zones emanate from land territory — not the other way around.

Local officials in Kalayaan town also objected to the remarks. Vice Mayor Maurice Phillip Alexis Albayda said the municipality plans to seek the removal of Marcoleta’s comments from Senate records.

“We are offended and insulted for our brave citizens,” Albayda said, adding that a resolution will be filed requesting the Senate Secretariat to strike the remarks from the record.