The guided-missile destroyer Hohhot (Hull 161) attached to a destroyer flotilla with the navy under the PLA Southern Theater Command steams in waters of the South China Sea during a maritime training exercise in Mid-July, 2019. Photo:China Military

The Chinese People's Liberation Army (PLA) on Tuesday expelled a US warship that trespassed into Chinese territorial waters in the Xisha Islands of the South China Sea, while experts said Wednesday that recent US naval activities in the South China Sea are a sign that the US is losing control in the region and wants to flex its muscles to gain influence in the region.

US guided missile destroyer McCampbell on Tuesday trespassed into China's territorial waters in the Xisha Islands, and the PLA Southern Theater Command organized naval and aerial forces to follow its entire course, identified the ship, warned and expelled it, said Senior Colonel Li Huamin, a spokesperson of the PLA Southern Theater Command, on Wednesday.

China has undisputed sovereignty over the islands in the South China Sea and nearby waters, and the Chinese military remains highly vigilant at all times and will take any necessary measure to resolutely safeguard national sovereignty and peace and stability in the South China Sea, Li Huamin said.

The US sees the South China Sea as the  "main battlefield" against China and is expected to increase actions even further in the future, because it has increasingly lost influence and control over the South China Sea, Li Jie, a Beijing-based naval expert, told the Global Times on Wednesday.

Countries in the South China Sea, such as the Philippines, are becoming less dependent on the US, so the US is losing leverage and has no option but to increase presence and exert influence on its own by sending warships, Li Jie said.

This is not the first time the US has sent a warship to the South China Sea in 2020.

On January 25, the US littoral combat ship Montgomery sailed near the Nansha Islands in the South China Sea, and was also expelled by Chinese forces.

The US side is using "freedom of navigation" as an excuse and repeatedly entering the South China Sea to flex its muscles and make trouble, which are acts of hegemony that violate international law and threaten peace and stability in the region, PLA Southern Theater Command spokesperson Li Huamin said on Wednesday.

As the PLA Navy gains far sea capability, it can also conduct "freedom of navigation" operations in international waters near the US, according to international law, to counter US provocation in its own way, Li Jie said.

From January to February, a far sea joint training fleet of the Chinese PLA Navy conducted a 41-day training mission that crossed the International Date Line deep into the Pacific Ocean, a region of international waters where the US has always thought of itself as a major influence, analysts said.

The US also accused the fleet of using lasers on its patrol aircraft near Guam, but it was the US aircraft that had conducted repeated close-in reconnaissance that interrupted the Chinese fleet's normal navigation and training in the first place.