The guided-missile frigates Mianyang and Suining attached to a frigate flotilla with the navy under the PLA Southern Theater Command steam in astern formation during a maritime combat training exercise in mid July, 2023. (eng.chinamil.com.cn/Photo by Ge Hanqiang and Zhang Weifeng)

The Chinese People's Liberation Army (PLA) was at the scene and on high alert when the US and Philippines launched a joint patrol in the South China Sea on Tuesday, with experts saying on Thursday that the PLA's presence deterred potential provocations and displayed China's capabilities in safeguarding national sovereignty, security and maritime interests.

The frigate Yuncheng affiliated with the navy of the PLA Southern Theater Command has been conducting a routine patrol in waters in the South China Sea since Tuesday, Senior Colonel Tian Junli, a spokesperson of the command, said in a press release on Thursday.

During the PLA warship's patrol, the Philippines rallied forces from outside the region and conducted a patrol in the South China Sea, stirred up tensions and troubles and hyped the event, Tian said.

The Philippines' move sabotaged regional peace and stability, and violated the spirit of the Declaration on the Conduct of Parties in the South China Sea, the spokesperson said.

"The command troops maintained high alert to firmly defend national sovereignty, security and maritime interests, and firmly safeguard peace and stability in the South China Sea," Tian said.

Tian's statement came after the Philippines launched a three-day joint air and maritime patrol with the US on Tuesday stretching from the Philippines' northernmost point near the island of Taiwan to the South China Sea, Reuters reported on the day.

Participating forces included three naval vessels, two FA-50 light combat aircraft and an A-29B light attack plane from the Philippine side, and a littoral combat ship and a P-8A Poseidon maritime patrol and reconnaissance aircraft from the US side, Reuters said.

Wei Dongxu, a Beijing-based military expert, told the Global Times that the US and Philippine forces deployed in the joint patrol have only limited capabilities.

A PLA Navy Type 054A frigate and a Y-9 surveillance aircraft kept watch on the US-Philippines joint patrol, Philippine Daily Inquirer reported on Thursday.

Zhang Junshe, a Chinese naval expert, told the Global Times on Thursday that the PLA presence during the US-Philippine joint patrol served as a deterrent force, and showed that China has the capability in safeguarding national sovereignty, security and maritime interests.

The Philippines' rallying of forces from outside the region only gave them the chance to interfere in the South China Sea issue and sabotage peace and stability in the region, which is also harmful to the Philippines' own national sovereignty and security, Zhang said.

The only right path for the Philippines is to return to talks and negotiations with China and resolve disputes through peaceful means, Zhang said. "The more the Philippines provokes, the heavier it will end up landing," he said.