The People's Liberation Army conducted combat readiness patrols on Sunday in the territorial waters, airspace, and surrounding areas of China's Huangyan Island in the South China Sea.

This was the third of such operations conducted by the Chinese military near the island, which an expert said was designed to send a strong signal that China takes concrete actions to safeguard national sovereignty and territorial integrity.

The PLA's Southern Theater Command announced the operation in a statement released on Sunday.

It said that since December, the theater command has been organizing naval and air forces to continuously strengthen patrols and vigilance around the territorial waters and airspace of Huangyan Island.

This effort has further enhanced the control over the relevant maritime and airspace areas, resolutely safeguarding national sovereignty and security and firmly maintaining peace and stability in the South China Sea, the statement said.

Liu Lin, a professor of international strategy at the Party School of the Central Committee of the Communist Party of China, said that combat readiness patrols are a military term referring to patrols conducted in a state of combat preparation, which is higher than regular patrols.

"In such operations, both front-line and rear forces, including command, communication, firepower, and reconnaissance systems, are maintained in a state of readiness for combat," she said, noting that these patrols are conducted to respond to "any potential emergencies".

Prior to this operation, the Southern Theater Command had conducted two combat readiness patrols in the territorial waters or airspace of Huangyan Island in mid and late November, respectively.

On Nov 8, Philippine President Ferdinand Marcos Jr signed the Maritime Zones Act and the Archipelagic Sea Lanes Act, attempting to unlawfully include China's Huangyan Island and most of the islands and reefs of the Nansha Islands, along with related waters, in its maritime zones.

Two days later, the Chinese government released baselines for the territorial sea adjacent to Huangyan Island in accordance with international law, including the United Nations Convention on the Law of the Sea, and the Law of the People's Republic of China on the Territorial Sea and the Contiguous Zone.

Liu said that the PLA's combat readiness patrols are intended to enhance control over the maritime and airspace areas of Huangyan Island.

"The provocations by the Philippines around the maritime and airspace areas of Huangyan Island have been frequent in recent times. Therefore, it is indeed necessary and urgent for China to strengthen control over these areas through combat readiness patrols," she said.

According to the China Coast Guard, since October, the Philippines side has attempted three times to intrude into the maritime and airspace around Huangyan Island using aircraft or government vessels.

On Dec 19, a Philippine C-208 aircraft illegally entered the airspace over Huangyan Island and was driven away by the China Coast Guard.

Chinese Defense Ministry spokesman Zhang Xiaogang on Thursday also responded to recent comments of the Philippine Coast Guard spokesperson, who claimed that the giant vessels of the China Coast Guard attacked the small vessels of the Philippine Coast Guard and that these acts of intimidation and spreading of misinformation aim at hindering the activities of the Philippine fishermen.

Zhang said the Philippines' efforts to play victim to elicit sympathy from and confuse the international community will never work.

He stressed that China has indisputable sovereignty over South China Sea islands and its adjacent waters.

Zhang noted that the maritime disputes between China and the Philippines have nothing to do with the size of countries, but the merits of fact matter.

"The Philippine side repeatedly organized its coast guard vessels and fishing boats to violate China's territorial sovereignty and maritime rights and interests and undermine peace and stability in the South China Sea," he said.

"We urge the Philippine side to change course and return to the right track of resolving issues through negotiation and consultation."

jiangchenglong@chinadaily.com.cn