A US official told CNN that the guided missile destroyer USS Higgins and the USS Antietam cruiser sailed 12 miles from four of the Paracel Islands in what the US Navy UU Calls a "freedom of navigation operation", which are designed to enforce the right of free pbadage in international waters.
China has strengthened many of the islands in the South China Sea in recent years, military installations and other expanded using land reclamation.
Beijing says that much of the South China Sea is its sovereign territory, claims that the majority of the international community is false.
Vietnam, the Philippines, Taiwan, Indonesia, Malaysia and Brunei also claim parts of the islands of the South China Sea.
An international court ruled in 2016 that most of Beijing's claims in the South China Sea were illegal, but that decision has not significantly affected the status quo on the ground.
Washington is committed to the freedom of navigation operations to enforce the right of free pbadage in disputed waters.
Barbara Starr of CNN contributed to this report.