Beijing claims sovereignty over almost all of the region but this clashes with rival claims from five of its neighbours. The United States rejects Chinese sovereignty over the world’s busiest shipping lane and regularly sends warships on “freedom of navigation” patrols through the area.
USS Theodore Roosevelt is being accompanied by USS Bunker Hill, a guided-missile cruiser, and Arleigh Burke class destroyers USS Russell and USS John Finn.
The US said the mission was taking place to “ensure freedom of the seas, build partnerships that foster maritime security”.
Rear Admiral Doug Verissimo, who is commanding the carrier group, added: “After sailing through these waters throughout my 30-year career, it’s great to be in the South China Sea again, conducting routine operations, promoting freedom of the seas, and reassuring allies and partners.
“With two-thirds of the world’s trade travelling through this very important region, it is vital that we maintain our presence and continue to promote the rules-based order which has allowed us all to prosper.”
On Sunday, Chinese combat aircraft made a major incursion into Taiwanese airspace for the second day running.
The operation involved 15 aircraft including 12 fighter jets.
Taiwanese forces warned the intruders away and prepared missiles as a precaution.
China regards Taiwan, which is situated off its eastern seaboard, as an integral part of its territory and has threatened military action to bring it under control.
READ MORE: Fears of open WAR surge as Beijing fortifies South China Sea island
“We urge Beijing to cease its military, diplomatic, and economic pressure against Taiwan and instead engage in meaningful dialogue with Taiwan’s democratically elected representatives.”
On Friday, China passed a new law allowing its coast guard to open fire on foreign vessels in what it considers to be its territorial waters.
As well as the South China Sea Beijing claims sovereignty over a number of East China Sea islands which are currently controlled by Japan.
Speaking to CNN Christian Le Miere, a maritime security expert, warned the new law “strikes at the heart” of the US policy of supporting freedom of navigation.
He added: “China’s coast guard is already doing most of the heavy lifting in maritime coercion in the near seas, so it’s worth examining the new legislation just passed on this issue.”
On Tuesday, Antony Blinken, Joe Biden’s incoming secretary of state, said there is “no doubt” China poses the biggest threat to the US during his Senate confirmation hearing.