American aircraft carrier USS John C. Stennis returned for patrol in the South China Sea as tensions over a territorial dispute heightened in the region, according to reports on Thursday. The Pentagon is also expected to deploy warplanes in the Philippines this week to counter assertive China.

According to the U.S. Pacific Fleet, the carrier has been in the South China Sea for about two weeks for flight operations and training, Navy Times reported. Defense Secretary Ashton Carter said he will visit Stennis Friday.

“With each Balikatan [joint Washington-Manila military exercises] and each cruise by the Stennis, with each new multilateral exercise and each new defense agreement, we add a stitch to the fabric of the region’s security network,” Carter said, according to Reuters. “This is the network - peaceful, principled, and inclusive - America continues to stand for, and stand with.”

The Philippines and the U.S. have begun joint patrols in the South China Sea, Carter said, adding that China’s activities are causing “anxiety and raising regional tensions.”

“Countries across the Asia-Pacific are voicing concern with China’s land reclamation, which stands out in size and scope, as well as its militarization in the South China Sea,” Carter said, according to Bloomberg.

The Pentagon will also deploy six aircraft and three helicopters with 200 pilots and crew members, at the former Clark Air Base, north of Manila, the New York Times reported. The aircraft fleet includes five Warthog ground-attack planes, three search-and-rescue helicopters and a plane regularly in use to transport Special Operations forces, the report added.

China, which has laid claims to most of the South China Sea, has consistently blamed the U.S. government of militarizing the contested region. However, the Pentagon maintains that it will continue to sail through it because the waters have long been considered international waterways. China has called the patrols provocative.

The long debated region of the South China Sea has been claimed by Brunei, China, Malaysia, the Philippines, Taiwan and Vietnam. Beijing has been expanding its presence in the disputed region and has built three runways on the Spratly archipelago. However, China has consistently defended its actions, saying it does not have any intentions of starting a conflict and that its aircraft facilities will maintain safety in the region.