A United States destroyer reportedly patrolled the Paracel Islands in the South China Sea Friday, a major challenge to China’s authority and claim to the hotly contested waterway, U.S. officials told Navy Times.

Located in the middle of the South China Sea between China, the Philippines and Vietnam, the move was seen as a direct challenge to China and comes at a time when the U.S. and President Barack Obama are looking to pivot and extend their presence in the region.

Officials told Navy Times the patrol by the destroyer USS Decatur did not break the 12-mile “territorial limit,” or rather the common international waters barrier. If the patrol did cross the 12-mile barrier, it would be considered a “freedom of navigation operation,” which is approved by the highest levels of the military and allows the U.S. to enter foreign countries’ waters.

China has long considered the important body of water to be under its jurisdiction, and has thwarted and challenged a United Nations-backed tribunal’s ruling from earlier this year that said it in fact does not have outright control of the South China Sea. Earlier this month, a state-run Chinese company said it was working a small nuclear power plant that could be easily transported around the South China Sea or anywhere else.

"USS Decatur (DDG 73) conducted this transit in a routine, lawful manner without ship escorts and without incident on Oct. 21," Defense Department spokesman Cmdr. Gary Ross told NavyTimes. "The United States conducts these routine operations on a regular basis around the world, in full compliance with international law." 

While the U.S. says its actions were legal, China is unlikely to agree. The Paracel Islands are controlled and occupied by the Chinese, but also claimed by Taiwan and Vietnam.

The U.S. conducted drills in tandem with ally Japan in the South China Sea earlier this year, which China warned its long rival Japan not to do. Last month, China said Japan was “playing with fire” when it announced the exercises with the U.S.