A US Navy ship sailed by islands claimed by China in the South China Sea on Wednesday in an open challenge to Beijing’s disputed maritime claims in the region.

The USS Russell guided-missile destroyer “asserted navigational rights” on Wednesday when it sailed by the Spratly Islands, the U.S. 7th Fleet said in a statement.

The freedom of navigation operation “upheld the rights, freedoms and lawful uses of the sea recognized in international law by challenging unlawful restrictions on innocent passage imposed by China, Vietnam and Taiwan,” it said.

The Spratly Islands, an archipelago of islets, reefs and rocks within the South China Sea, face overlapping claims of sovereignty by China and several coastal nations including Taiwan, Malaysia, Vietnam, Brunei and the Philippines.

Three of those nations – China, Taiwan and Vietnam – require either permission or advance notification for military vessels to pass.

China lays claim to much of the South China Sea through its so-called Nine-Dash-Line maps, an assertion the United Nations ruled in 2016 was without any legal basis.

The 7th Fleet said Wednesday “unlawful and sweeping maritime claims” in the body of water pose a serious threat to the freedom of the seas for navigation, overflights and free trade.

“The United States upholds freedom of navigation as a principle,” it said. “As long as some countries continue to assert maritime claims that are inconsistent with international law … the United States will continue to defend those rights and freedoms.”

Under the Trump administration, the United States took a strong stance against China, wholly rejecting Beijing’s claims to the South China Sea in July and accusing it of conducting a “campaign of bullying to control them.”

Trump’s Treasury also imposed sanctions against Chinese companies, executives and military on accusations of intimidating Beijing’s neighbors to achieve unimpeded access to the resource-rich area.

The USS Russell’s voyage on Wednesday comes after President Jose Biden, who was inaugurated on Jan. 20, said earlier this month that his administration will “take on directly the challenges posed by our prosperity, security and democratic values by our most serious competitor, China.”

“We’ll confront China’s economic abuses, counter its aggressive, coercive action to push back on China’s attack on human rights, intellectual property and global governance,” he said in a speech on US foreign policy on Feb. 4 in Washington, DC.