The People's Liberation Army's Southern Theater Command conducted a routine patrol in the South China Sea on Wednesday, a day after the Philippines and United States militaries conducted a joint exercise in the region.

Tian Junli, spokesperson for the Southern Theater Command, announced the operation on Wednesday evening, accusing the Philippines of colluding with outside countries to organize "so-called joint patrols", which Tian claimed destabilize the region.

The Philippines' actions, Tian said, were an attempt to endorse its "illegal claims" in the South China Sea and undermine China's maritime rights and interests. "The theater command forces remain on high alert, resolutely defending national territorial sovereignty and maritime rights and interests. Any military activities that disrupt the South China Sea are fully under control," the spokesperson said.

On Tuesday, the air forces of the Philippines and the US held "joint patrols" over the South China Sea, according to the Philippines Air Force.

The same day, the PLA's Southern Theater Command's Air Force conducted a routine patrol over Huangyan Island in the South China Sea. Li Jianjian, a spokesperson for the theater command's Air Force, said the Philippines had worked with outside countries to organize "joint patrols", further undermining peace and stability in the region.

On Monday, Tian addressed the passage of a Chinese naval fleet through the Basilan Strait near the Philippines. Tian said the theater command had organized naval and air forces for far-sea exercises via the Basilan Strait. "The relevant operations were conducted in a safe, standardized and professional manner, fully in accordance with international law and international practice," Tian said.

Tian criticized the Philippines for "slandering and hyping up" the normal passage of the Chinese naval fleet, adding that such actions violated the normal navigation rights of other countries, including China.