Taipei: Analysts think that China sends an increasing number of warplanes into Taiwan's air defence zone to send a message to the US rather than threaten the island itself as the US is in favour of a democratic, independent Taiwan.

According to the Voice of America, a senior fellow at the East-West Centre think tank in Hawaii, Denny Roy said, "The dominant narrative inside China is that the USA is increasingly promoting Taiwan independence as a way to contain China."

"The Chinese are now watching for evidence that would confirm this. Lacking a creative new approach, Beijing has doubled down on what has become its standard form of hostile military signalling," he added.

Since mid-2020, the People's Liberation Army-Air Force has flown a small number of fighters and bombers over part of the Taiwanese air defence identification zone (ADIZ) almost daily, Voice of America reported.

Last week, China sent 29 warplanes into Taiwan's air defence zone, marking the third-largest fly-by in the country this year.

The warplanes, which include 17 fighter jets, six bombers and other supporting aircraft, entered the island's air defence identification zone on Tuesday from the southwest, the island's defence ministry said.

Earlier that, a US Navy P-8A Poseidon reconnaissance plane flew over the Taiwan Strait.

The flyover of a surveillance plane over the Taiwan Strait was a demonstration of the US "commitment to a free and open Indo-Pacific," amid recurrent Chinese incursion in Taiwan's ADIZ, US Indo-Pacific Command said in a statement.

On June 13, China's foreign ministry said Beijing has sovereignty over the Taiwan Strait, drawing a rebuttal from the United States four days later.

The United States further called on China on June 17 to end its "provocative actions" and to "respect international law" in the adjacent South China Sea, the Voice of America reported.

Washington considers the strait between Taiwan and China international waters that should be open to its Asia allies from Tokyo through Manila. The US government informally supports Taiwan, though the two lack formal diplomatic ties.

Beijing separately claims most of the South China Sea, a resource-rich waterway disputed by Taiwan and four Southeast Asian countries, while Taiwan believes that China's claim of Sovereignty over the Taiwan Strait is false and the only waters over which any country has full sovereignty are its 12-nautical mile territorial waters, Voice of America reported.

A week earlier, Washington had approved plans to sell warship parts and related technical support to Taiwan worth USD 120 million. Last month, US President Joe Biden said the US would defend Taiwan if China attacked.

"Originally, when the PLA airplanes or fighters and the like started visiting the ADIZ, it was for a different reason, but nowadays the frequency has increased for a recent reason," said Lin Chong-pin, a retired strategic studies professor in Taiwan.

Taiwan and mainland China have been governed separately since the defeated Nationalists retreated to the island at the end of the Chinese civil war of the 1940s.

But China's ruling Chinese Communist Party (CCP) views the self-ruled island as part of its territory -- despite having never controlled it. Beijing says it will use force, if needed, to unite the two sides.

The issue of Taiwan has been at the forefront of US-China relations in recent months.

Tensions between Washington, which is committed to supporting the island's self-defence, and Beijing over Taiwan were in the open earlier this month when their respective defence chiefs met at the Shangri-La Dialogue defence conference in Singapore.