The U.S. Navy announced the group began routine patrols Saturday. The group includes Nimitz-class aircraft carrier USS Carl Vinson.
The area where the U.S. group is patrolling is a disputed area; China has been asserting its rule over the waterway despite territorial claims from a number of other east Asian nations.
Nations competing with China for claims to parts of the South China Sea include Cambodia, Indonesia, Malaysia, the Philippines, Singapore, Thailand and Vietnam. Taiwan also claims part of the area.
The U.S. strike group trained off the coasts of Hawaii and Guam in preparation for the patrols.