The U.S. Navy said Saturday that the aircraft carriers USS Nimitz and USS Ronald Reagan were carrying out military drills in the disputed South China Sea “to support a free and open Indo-Pacific,” according to Reuters. The exercises come a day after China began conducting its own military exercises in the disputed sea, of which China has claimed 90 percent despite protests from the U.S. and regional countries. “The purpose is to show an unambiguous signal to our partners and allies that we are committed to regional security and stability,” Rear Admiral George M. Wikoff told the Wall Street Journal when asked if the U.S. exercises are a response to China’s actions.