The US has sent at least four military aircraft to recover the top-secret components of its crashed F-35C fighter jet in the South China Sea, a Beijing-based think tank said.

"[Salvage work] for the crashed F-35C seems to be beginning" the SCS Probing Initiative (SCSPI) tweeted on Saturday, citing satellite images.

This comes after the US Navy revealed last Monday that an F-35C Lightning II - its most advanced stealth fighter jet - had fallen into the sea after a "landing mishap" on the USS Carl Vinson aircraft carrier during routine operations.

Do you have questions about the biggest topics and trends from around the world? Get the answers with SCMP Knowledge, our new platform of curated content with explainers, FAQs, analyses and infographics brought to you by our award-winning team.

At least four US Air Force CV-22B Osprey tilt-rotor aircraft, believed to have been deployed from American bases in Japan and the Philippines, were spotted "heading to the area where the carrier exercises had taken place", SCSPI said in its Twitter post.

The Salvage of the crashed F-35C seems to be beginning. Today, at least 4 USAF CV-22B Osprey from the Philippines and Japan are heading to the area where the carrier exercises had taken place. Get some equipments to the sea first? Jan 29. pic.twitter.com/zbY0nPrnhC

- SCS Probing Initiative (@SCS_PI) January 29, 2022

Earlier on Saturday, the Japanese Coast Guard issued a navigational warning that salvage operations were being carried out in an area in the northern part of the South China Sea "until further notice".

This comes days after a photo of an F-35 floating on the water with an open cockpit canopy appeared on Reddit and soon began to be circulated online.

On Friday, the US Navy confirmed that the leaked photo - and a related video shared on Twitter - did show the F-35C hitting the USS Carl Vinson flight deck and floating in the South China.

Seven military personnel, including the pilot who ejected safely, were injured in the incident. The US Navy said it was "making recovery operations arrangements" for the stricken aircraft.

The F-35 fleet, with three variants including the carrier-based F-35C, represents the most sophisticated military aircraft in the world. Designed to utilise stealth technology and systems integration, it is also America's most expensive weapons system, with an average price tag of over US$100 million each.

The F-35C is the world's most sophisticated military aircraft. Photo: Reuters alt=The F-35C is the world's most sophisticated military aircraft. Photo: Reuters>

According to the Centre for Arms Control and Non-Proliferation, the F-35 fleet is the second largest in the US Air Force inventory after the F-16.

This is the second crash involving a Lockheed Martin-made F-35 jet in just over two months. In November, a British F35B crashed into the Mediterranean following a slow take-off from the Royal Navy aircraft carrier HMS Queen Elizabeth.

The US crash also sparked media speculation on whether China, now identified as a major strategic competitor by the Pentagon, would race to recover the jet for access to the stealth technology. But Beijing has rejected such claims.

"We have no interest in their plane," Chinese foreign ministry spokesman Zhao Lijian said on Thursday.

Meanwhile, Chinese military observers said salvage operations might prove difficult because of the complicated underwater conditions in the South China Sea.

The resource-rich South China Sea is criss-crossed by busy shipping lanes and rival territorial claims from China and its Southeast Asian neighbours.

The renewed US focus on the "Indo-Pacific" to counter China's growing influence has also set up the waterways as a major arena of great power rivalry. Both sides have stepped up their military presence in the strategically important region, and the US has sharply scaled up its "freedom of navigation" operations in international waters there.

Earlier this month, the US Indo-Pacific Command announced that its USS Abraham Lincoln and USS Carl Vinson aircraft carrier strike groups had carried out joint operations in the South China Sea on January 23 to "strengthen maritime integrated-at-sea operations and combat readiness".

Rear Admiral Dan Martin, commander of the strike group led by the USS Carl Vinson, said the operations were part of the US' commitment to "deterring those who challenge the shared vision of a free and open Indo-Pacific now and into the long-term future".

US report dismisses Beijing's claim to South China Sea 'historical rights'

Two weeks ago, the Chinese People's Liberation Army (PLA) accused the US of "provocative actions" that could lead to "serious consequences", saying it had tracked the guided-missile destroyer USS Benfold sailing through the disputed Paracel Islands, known as Xisha Islands in China.

The US Navy denied the claims, saying that its warship's passage was "innocent", its freedom of navigation operation in accordance with international law, and that such operations would continue.

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.

Copyright (c) 2022. South China Morning Post Publishers Ltd. All rights reserved.