China’s military said on Tuesday it had sent forces to watch a US warship that “illegally” entered waters around a disputed shoal in the South China Sea, while further north in the waterway, Taiwan reported a standoff with a Chinese ship.

Axar.az informs, citing Reuters, China views almost all of the busy South China Sea as its own territory, despite overlapping claims by Brunei, Malaysia, the Philippines, Taiwan and Vietnam, with recent tension most pronounced between Beijing and Manila.

The Chinese military’s Southern Theatre Command said the USS Charleston “illegally intruded” into waters adjacent to Sabina Shoal in the Spratly Islands without Chinese government approval in the early hours of Tuesday.

“The US action infringes upon China’s sovereign rights and interests, jeopardizes maritime security, and is detrimental to regional peace and stability,” it said in a statement.

“The US side should immediately cease such activities.”

China’s navy dispatched forces to track and monitor the ship, it added.