The Japan-based Antietam, officials said, was conducting a “routine patrol” separate from the Stennis, following up patrols conducted by the destroyer McCambell and the dock landing ship Ashland in late February.

The stand-off has been heating up on both sides. After news in February that the Chinese deployed an advanced surface-to-air missile battery to the Paracel Islands, U.S. Pacific Command head Adm. Harry Harris told lawmakers that China was militarizing the South China Sea.

“In my opinion China is clearly militarizing the South China Sea,” Harris testified on Feb. 24. “You’d have to believe in a flat Earth to believe otherwise.”

Overnight, Chinese officials dismissed claims that China was militarizing the region, pointing to the Stennis’s patrol as evidence that the U.S. was to blame for the increased military tensions.

“The accusation [that China is militarizing the region] can lead to a miscalculation of the situation,” said Fu Ying, a spokeswoman for China’s National People’s Congress. “If you take a look at the matter closely, it’s the US sending the most advanced aircraft and military vessels to the South China Sea.”