America sent a nuclear-powered aircraft carrier on a cruise through the South China Sea today, projecting its power in waters that are fast becoming a focal point of its strategic rivalry with Beijing.

The USS George Washington’s mission could raise hackles in China, which is locked in disputes with Vietnam, the Philippines and other Governments over ownership of islands in the region.

It will likely reassure the jittery smaller nations of Washington’s support in their tussles with China, whose growing economic and military might is leading to a greater assertiveness in pressing its claims in the South China Sea.

The US is building closer economic and military alliances with Vietnam and other nations in the region as part of a “pivot” away from West Asia to Asia.

China is also locked in an unexpectedly fierce dispute with American ally Japan over the ownership of islands in the nearby East China Sea. On Friday, Beijing staged military exercises near the islands to demonstrate its ability to enforce its claims.

China claims nearly all of the South China Sea, where the US says it has a national interest in ensuring freedom of navigation in an area crossed by vital shipping lanes.

Vietnam, the Philippines and several other Asian nations also claim parts of the sea.

The US Navy regularly patrols the Asia-Pacific region, and the trip by the George Washington off the coast of Vietnam is its second in two years.

A second aircraft carrier, the USS John C. Stennis, is also conducting operations in the western Pacific region, according to the US Pacific Fleet.

“China will take this as another expression by the US of its desire to maintain regional domination,” said Denny Roy, a senior fellow at the East-West Center in Hawaii.

“The US also wants to send a message to the region that it is here for the long haul .... and that it wants to back up international law.”

Vietnam is pleased to accept help from its one-time foe America as a hedge against its giant neighbour China. It has reacted angrily to recent moves by Beijing to establish a garrison on one of the Paracel islands, which Vietnam also claims.

The US also criticised the move by Beijing.