(CNN) — The US Navy has sent a destroyer near a disputed island in the South China Sea that Beijing has fortified with military installations to claim territorial rights in the region.

When navigation occurred Chinese military encircles Taiwan for third day1,600 kilometers near the northern entrance to the South China Sea, in response to a brief US visit by Taiwan’s president.

The US Navy’s Seventh Fleet said in a statement Monday that the guided-missile destroyer USS Milius passed within 12 nautical miles of Mischief Reef in China’s Spratly Islands, also known as the Nansha Islands, the internationally recognized limit of the nation’s territorial waters.

Mischief Reef, located in the Philippine Exclusive Economic Zone, is claimed by Vietnam and Taiwan. But Beijing has asserted its rights by building up the island and putting up military infrastructure.

The US says such actions violate the Convention on the Law of the Sea.

“A territorial sea has no claim to places such as naturally occurring high-tide submersible reefs. Land reclamation efforts, facilities and structures built on Mischief Reef do not alter this character under international law,” the US 7th Fleet said in a statement.

China claims the entire vast South China Sea as part of its territorial waters, including several islands and remote inlets in disputed waters, many of which Beijing has militarized.

A spokesman for the People’s Liberation Army’s Southern Theater Command said the US destroyer had “illegally trespassed” in China’s waters near Mischief Reef, also known as Beijing Meiji Reef.

“China has indisputable sovereignty over islands in the South China Sea and their adjacent waters,” Air Force Senior Col. Tian Junli said in a statement.

A US destroyer Freedom of Navigation Operation (FONOP) protected the right of any nation’s ships to operate in the area, the 7th Fleet statement said.

US warships regularly conduct this type of FONOP in the South China Sea Milius’ second in three weeksIt sailed near the Paracel Islands, also known as the Jisha Islands in China, in the northern part of the South China Sea on March 23.

“Regardless of the location of excessive maritime claims and regardless of current events, the United States will fly, lead and operate wherever international law permits,” the Seventh Fleet said in a statement Monday.

After the FONOP in March, Beijing said the US had violated its sovereignty while “undermining peace and stability in the South China Sea,” Chinese Defense Ministry spokesman Tan Kefei said.

The US FONOP on Monday came as Chinese forces entered the third day of large-scale military exercises around the island of Taiwan, a self-governing democracy north of the South China Sea that the ruling Chinese Communist Party claims as its territory. He never ruled.

Beijing began operations around Taiwan on Saturday, a day after Taiwanese President Tsai Ing-wen returned from a 10-day trip to Central America and the United States, where she met with House of Representatives Speaker Kevin McCarthy.

Beijing has repeatedly warned against Sai’s meeting with McCarthy and has previously threatened to take “firm and decisive action” if it happens.

— CNN’s Beijing bureau contributed to this report.