WASHINGTON (Reuters) - A U.S. Navy destroyer sailed near islands claimed by China in the South China Sea on Wednesday, the U.S. military said, a move that Beijing condemned as an illegal attempt by Washington at “maritime hegemony”.

The busy waterway is one of a growing number of flashpoints in the U.S.-Chinese relationship, which include an escalating trade war, American sanctions on China’s military, and U.S. relations with Taiwan.

Reuters reported on Tuesday that China had denied a request for a U.S. Navy warship to visit the port city of Qingdao.

The U.S. Navy vessel Wayne E. Meyer, an Arleigh Burke-class guided missile destroyer, carried out the operation, traveling within 12 nautical miles (14 miles/22 km) of Fiery Cross and Mischief Reefs, Commander Reann Mommsen, a spokeswoman for the Japan-based U.S. Navy’s Seventh Fleet, said.

The operation was conducted “to challenge excessive maritime claims and preserve access to the waterways as governed by international law,” Mommsen said.

The U.S. military operation comes amid an increasingly bitter trade war between China and the United States that sharply escalated on Friday, with both sides leveling more tariffs on each other’s exports.

The U.S. military has a long-standing position that its operations are carried out worldwide, including in areas claimed by allies, and are separate from political considerations.

FILE PHOTO: The USS Wayne E. Meyer (DDG-108) Arleigh Burke-class Destroyer sits docked in San Diego, California, April 12, 2015. REUTERS/Louis Nastro/File Photo

Chinese military spokesman Li Huamin said in a statement early on Thursday that the U.S. vessel had encroached upon Chinese territorial waters near the Spratly Islands without the government’s permission and had been warned to leave.

“The facts prove that the United States’ so-called ‘freedom of navigation’ is actually an assertion of maritime hegemony that ignores international law, seriously harms China’s sovereignty and security interests, and seriously harms peace and stability in the South China Sea region,” Li said.

“We urge the U.S. side to immediately stop such kinds of provocative acts, to avoid causing unexpected incidents.”

China and the United States have traded barbs in the past over what Washington has said is Beijing’s militarization of the South China Sea by building military installations on artificial islands and reefs in disputed waters.

China’s claims in the South China Sea, through which about $5 trillion in ship-borne trade passes each year, are contested by Brunei, Malaysia, the Philippines, Taiwan and Vietnam.

Beijing says its construction is necessary for self-defense and that the United States is responsible for ratcheting up tensions by sending warships and military planes close to islands that Beijing claims.

Asked why China had denied the U.S. request for the Qingdao port visit, Defense Ministry spokesman Ren Guoqiang did not give a direct answer, saying only that they had been in communication with the United States through military and diplomatic channels.

Ren, speaking at a regular monthly news briefing, implied it was to do with the overall poor state of relations.

“We value developing the China-U.S. military-to-military relationship but the U.S. side should create positive conditions and atmosphere for the development of this relationship,” he added.

China’s 2019 defense spending will rise 7.5 percent from 2018, according to a budget report. Its military build-up has raised concerns among neighbors and Western allies, particularly with China becoming more assertive in territorial disputes in the East and South China Seas and over Taiwan, a self-ruled territory Beijing claims as its own.

The U.S. military last year put countering China, along with Russia, at the center of a new national defense strategy, shifting priorities after more than a decade-and-a-half of focusing on the fight against Islamist militants.

Vice President Mike Pence, in a visit to Iceland next week, will also have talks about “incursions” into the Arctic Circle by China and Russia, a senior Trump administration official said on Wednesday.