File photo: People pose for a group photo together after landing at the airfield on Yongshu Jiao in the Nansha Islands, Jan. 6, 2016. China successfully carried out test fights of two civilian aircraft on Jan. 6 on a newly-built airfield in the Nansha Islands of theSouth China Sea. (Xinhua file photo/Xing Guangli)

BEIJING, May 10 (Xinhua) -- China on Tuesday expressed "resolute opposition" to a U.S. warship patrol in the South China Sea near Yongshu Jiao in the Nansha Islands.

The U.S. warship, USS William P. Lawrence, illegally entered Chinese waters near the islands on Tuesday without the permission of the Chinese government, Foreign Ministry spokesman Lu Kang said, adding that the warship was monitored, tracked and issued with a warning.

According to a press release from the Defense Ministry later on Tuesday afternoon, two J-11 fighter jets and a Y-8 naval patrol plane flew over the waters on patrol. A destroyer, a missile frigate and a frigate identified the U.S. warship, warned and expelled it.

It is reported that Bill Urban, the spokesman for U.S. Department of Defense, said the freedom of navigation operation was a direct challenge to "excessive maritime claims of some claimants in the South China Sea."

"The action by the U.S. threatens China's sovereignty and security, endangers the safety of people and facilities on the reef and harms regional peace and stability," Lu said.

"China strongly opposes such action by the United States and will continue to take measures to safeguard our sovereignty and security," Lu said, adding that China and other coastal states in the South China Sea have been working together to keep navigation and overflight free in the South China Sea for a long time. In fact, freedom of navigation and overflight have never been problems.

According to Lu, the United States introduced freedom of navigation operations in 1979 before the signing of the UN Convention on the Law of the Sea (UNCLOS), a treaty to which the United States is still not a party. The purpose of these recurring "patrols" is to disrupt the order of the seas and oceans without adhering to the UN convention.

The United States sends military vessels and aircraft on surveillance missions against China as simple acts of provocation, said Lu, adding that the United States actually considers itself above the UNCLOS and these activities are opposed by many countries.

Lu said that the flexing of U.S. military muscle in the name of freedom of navigation is the biggest threat to peace and stability in the area.

Yang Yujun, a spokesperson for the Defense Ministry, said via a press release that the illegal entry of the U.S. warship into Chinese waters was "severe provocation."

"We can't help but wonder how far the U.S. side will go in their militarization of the South China Sea and in sabotage of peace and stability," Yang said.

He added that the patrol exposed the true intent of the U.S. side to agitate the regional situation and to profit from it. It also showed that it is both reasonable and necessary for China to deploy defensive facilities on the islands.

China will strengthen naval and air force patrols and reinforce defense capabilities to protect national sovereignty, security and the peace and stability of the South China Sea, Yang said.