The U.S. Navy said Tuesday that it had sailed a warship near the contested Spratly Islands in the South China Sea — home to fortified islands built by China — on Saturday, in what was believed to be its first freedom of navigation operation (FONOP) of 2020.

A spokesman for the U.S. Navy's 7th Fleet told The Japan Times that the USS Montgomery, an advanced littoral combat ship, had "asserted navigational rights and freedoms in the Spratly Islands, consistent with international law."

The latest FONOP "upheld the rights, freedoms and lawful uses of the sea," 7th Fleet spokesman Lt. Joe Keiley said, adding that the Montgomery had "challenged the restrictions on innocent passage imposed by China, Vietnam, and Taiwan."