The United States has sent an aircraft carrier strike group and a landing helicopter dock group to the South China Sea where the Chinese aircraft carrier Shandong exercised two weeks ago, adding new tension to the hotspot.

The Nimitz-class aircraft carrier USS Carl Vinson and the Wasp-class USS Essex, as well as their respective escorting vessels, entered the southern waters of the South China Sea on Tuesday evening, according to Beijing-based think tank South China Sea Strategic Situation Probing Initiative, which monitors open-source ship tracking information.

The US Navy has yet to announce its plans but the two major attack groups are expected to join forces and probably operate together.

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Two US dual carrier strike group (CSG) exercises took place in the South China Sea in July 2020 and February 2021, while in October last year the Carl Vinson CSG was on a joint exercise with the Japanese helicopter carrier JS Kaga in the region.

The latest deployment comes just a few weeks after the PLA Navy held simultaneous drills for its two aircraft carriers, one in the South China Sea. It is also only three weeks ahead of the Beijing Winter Olympics and the Lunar New Year, when China will be hoping to avoid a build-up of military tensions in its backyard.

According the US Navy, the Carl Vinson strike group last week was in the Celebes Sea - between the Philippines, Indonesia and Malaysia - with nine plane squadrons from Carrier Air Wing 2 on board, including one stealth fighter F-35C and its team.

The group includes the Ticonderoga-class guided missile cruiser USS Lake Champlain and the Destroyer Squadron 1, consisting of five Arleigh Burke-class guided missile destroyers.

The USS Essex amphibious ready group (ARG) left its three-and-a-half month mission in the Middle East last week and crossed the Strait of Malacca from the Indian Ocean over the weekend on its way to the exercise.

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The USS Essex is accompanied by the amphibious transport dock USS Portland and amphibious dock landing ship USS Pearl Harbor. The 11th Marine Expeditionary Unit and Amphibious Squadron is also taking part.

China's Kuznetsov-class aircraft carrier the Shandong has returned to its home port in Sanya, on the southern island province of Hainan, after "realistic combat-oriented exercises" - including arrested landing of fighter jets, damage control and maritime search and rescue - in the South China Sea at the end of December.

Footage of the Shandong at Sanya was included in a state television report on January 5 in which Chinese President Xi Jinping declared the opening of this year's military training programme.

Sister ship Liaoning has also returned to its home port of Qingdao, in the eastern province of Shandong, according to the PLA Navy.

While the Shandong carrier was on South China Sea exercises in December, the Liaoning was in the Western Pacific Ocean. No US aircraft carriers were in the region at the time.

This article originally appeared in the South China Morning Post (SCMP), the most authoritative voice reporting on China and Asia for more than a century. For more SCMP stories, please explore the SCMP app or visit the SCMP's Facebook and Twitter pages. Copyright © 2022 South China Morning Post Publishers Ltd. All rights reserved.

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