The U.S. Navy has sent a warship through the Taiwan Strait for the first time since September, in a move likely to anger China.

The Yokosuka, Kanagawa Prefecture-based guided-missile cruiser USS Chancellorsville “conducted a routine Taiwan Strait transit on Tuesday,” the navy said in a statement.

“The ship’s routine transit demonstrates the U.S. commitment to a free and open Indo-Pacific,” it said, adding that the navy would “continue to operate anywhere international law allows.”

The U.S. has ramped up the frequency of its transits of the Taiwan Strait, sending navy warships and coast guard vessels through the strategic waterway at least nine times this year, much to the chagrin of Beijing.

In China’s defense white paper released in late July, Beijing said it will not renounce the use of force in efforts to reunify Taiwan with the mainland, noting that its armed forces are bolstering their military preparedness for such a contingency.

“The PLA will resolutely defeat anyone attempting to separate Taiwan from China and safeguard national unity at all costs,” the paper said, referring to the Chinese People’s Liberation Army.

Taiwan, a democratically governed island, split from Communist Party-ruled mainland China after the civil war ended in 1949. Beijing views Taiwan as a renegade province that must be brought back into the fold — by force if necessary.

Beijing has called Taiwan “the most important and sensitive issue in China-U.S. relations” and has bolstered its military presence near the island, sailing its sole operating aircraft carrier through the Taiwan Strait in January and March of last year and holding large-scale “encirclement” exercises and bomber training throughout last year and into this year.

The transit came as the top U.S. military officer, Joint Chiefs of Staff Chairman Gen. Mark Milley, was visiting Japan for a meeting with Prime Minister Shinzo Abe to help repair diplomatic relations with South Korea amid an ongoing trade and history spat between Tokyo and Seoul.

Defense Secretary Mark Esper, meanwhile, was set to begin on Thursday a four-nation Asia tour with stops in South Korea, Thailand, the Philippines and Vietnam, according to the Pentagon.