The U.S. Navy has dispatched an aircraft carrier and several ships accompanying it into the South China Sea in the last few days, a deployment of thousands of U.S. sailors to a region a top U.S. admiral said last week is increasingly militarized by China.

The USS John C. Stennis, the carrier, arrived in the South China Sea on Tuesday, Navy officials said. It is accompanied by the cruiser USS Mobile Bay and the destroyers USS Stockdale and USS Chung-Hoon, said Navy Cmdr. Clay Doss, a spokesman for U.S. Pacific Fleet. The ships arrived in the Western Pacific on Feb. 4 on a deployment from the West Coast of the United States.

Doss said the carrier is carrying out a routine patrol of the South China Sea, where China has in recent weeks moved Chinese fighter jets, military radar and surface-to-air missiles. The Navy will continue to appear in the South China Sea regularly, Doss said. Pacific Fleet ships spending a combined 700 days there last year.

Aside from the carrier group, the Japan-based USS Antietam, a cruiser, also is currently patrolling the South China Sea, Doss said. The USS McCambell, a destroyer, and the USS Ashland, an amphibious dock landing ship, completed similar patrols last week.

It is not clear if or when any of the ships will complete any freedom of navigation patrols. The Navy has carried out two controversial ones in the South China Sea since October, using destroyers to sail within 12 nautical miles of artificial islands claimed by China. Beijing has claimed the surrounding waters as its own, but the Pentagon has said it will continue to sail through them because they have long been considered international waterways. China has called the patrols provocative.