The San Diego-based aircraft carrier USS Carl Vinson and accompanying warships began patrolling the disputed South China Sea on Saturday, the Navy reported.
China has claimed a large area of the sea and fortified a number of small islands. The Navy did not say whether the strike group would travel near the islands.
On Wednesday China warned the United States not to challenge its sovereignty in the region.
The strike group entered the South China Sea after training off Hawaii and Guam and operations in the Philippine Sea.
“The training completed over the past few weeks has really brought the team together and improved our effectiveness and readiness as a strike group,” said Rear Adm. James Kilby, commander of the group.
“We are looking forward to demonstrating those capabilities while building upon existing strong relationships with our allies, partners and friends in the Indo-Asia-Pacific region, ” he said.
The Vinson last deployed to the Western-Pacific in 2015.