The U.S. Navy deployed aircraft carrier USS Carl Vinson to the South China Sea on Saturday despite China's warnings not to challenge its sovereignty.
China claims much of the sea as its own, despite claims by the Philippines, Vietnam, Malaysia, Taiwan and Brunei.
China ... firmly opposes any country's attempt to undermine China's sovereignty and security in the name of navigation and overflight.
China has been creating artificial islands in the sea since 2013, equipping many with military-grade weapons systems, USA Today reports.
China said it learned about the deployment of the ship on Wednesday, prompting the Foreign Ministry's warning.
The Vinson carrier boasts more than 60 aircraft, including F/A-18 fighter jets.
Secretary of State Rex Tillerson said China should be blocked from reaching those artificial islands during his confirmation hearing.
This isn't the first time the U.S. has sent a carrier to the sea. The USS Coronado held a training exercise in the sea last week, and the Vinson was in the sea in 2015, CNN reports.
Roughly $5 trillion in trade passes through the sea each year.
Did China ask us if it was OK to devalue their currency (making it hard for our companies to compete), heavily tax our products going into..— Donald J. Trump (@realDonaldTrump) December 4, 2016
President Trump repeatedly criticized China, including their involvement in the sea.