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 United States is building closer economic and military alliances with Vietnam and other nations in the region as part of a "pivot" away from the Middle East 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 U.S. 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 U.S. 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 U.S. Pacific Fleet.
"China will take this as another expression by the United States of its desire to maintain regional domination," said Denny Roy, a senior fellow at the East-West Center in Hawaii. "The U.S 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 neighbor 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 United States also criticized the move by Beijing.
"Vietnam requests China to respect the sovereignty of Vietnam and refrain from taking any other similar wrongdoings," the Foreign Ministry said this month.
While most analysts believe military confrontation in the waters is highly unlikely, they say tensions are likely to increase as China continues pressing its claims and building its navy.
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