MANILA, Philippines — Malacañang expressed concern over the warning of the United States that China might bring nuclear elements to its outposts in the South China Sea.

The US Department of Defense, in its annual report to the US Congress, warned that Beijing may soon install floating nuclear power stations on its military bases in the disputed waterway.

Presidential spokesperson Harry Roque said the Philippine government is concerned over any entry of nuclear weapons on Philippine territory.

"We are concerned about the possibility that any foreign power be it American, Russian, Chinese may bring nuclear warheads into our territory and into Asean, which is declared as a nuclear-free zone," Roque said in a press briefing Thursday.

Citing the Constitution, Roque stressed that the Philippines is a nuclear-free zone.

Section 8, Article 2 of the 1987 Constitution states that "The Philippines, consistent with the national interest, adopts and pursues a policy of freedom from nuclear weapons in its territory."

The Malacañang spokesman also noted that the whole Association of Southeast Asian Nations is a nuclear-free zone under the Treaty on the Southeast Asia Nuclear Weapon-Free Zone, which was signed.

Roque, however, said that the warning was only "US observation" and that the Philippines is in no position to verify such report.

"The important point to underscore is we have a nuclear-free policy and that should be applied to all countries, including the Americans, because the Americans have been using nuclear-powered [weapons] and have been stationing warships with nuclear capability as well," he said.

The Pentagon also reported that Beijing has invested resources to maintain a "limited, but survivable" nuclear force.

This is to ensure that the People's Liberation Army would have the capacity to deliver a damaging responsive nuclear strike.

"China’s nuclear weapons policy prioritizes the maintenance of a nuclear force able to survive a first strike and to respond with sufficient strength to inflict unacceptable damage on an enemy," the report read.