Taiwanese forces were on high alert in anticipation of Beijing's People's Liberation Army (PLA) staging war games in response to Lai's US stopovers and call with Republican House Speaker Mike Johnson.

Taiwan's defence ministry said the number of Chinese ships in the waters around the island exceeded Beijing's maritime response to then US House speaker Nancy Pelosi's visit to Taipei in 2022, which was the largest-ever war games.

In those drills, Beijing deployed ballistic missiles, fighter jets and warships in what analysts described as practice for a blockade and ultimate invasion of Taiwan -- and was a display of how far China's military had come since the last Taiwan Strait crisis in the mid-1990s.

Nearly 90 Chinese naval and coast guard ships were currently in waters along the so-called first island chain, which links Okinawa, Taiwan and the Philippines, a senior Taiwanese security official told AFP.

Taiwan's defence ministry said earlier it had also detected 47 Chinese aircraft near the island in the 24 hours to 6:00 am (2200 GMT).

That was the highest number of aircraft detected in a single day since a record 153 reported on October 15, after China staged major military drills in response to Lai's National Day speech days earlier.

Speaking in Tokyo, US Defense Secretary Lloyd Austin said Tuesday that China's "coercive behaviour" threatened regional stability.

"Now we're clear-eyed about the challenges to peace and stability in this region and worldwide," Austin said as he met his Japanese counterpart Gen Nakatani.

"That includes coercive behaviour by the People's Republic of China in the East China Sea and the South China Sea and elsewhere in the region," said Austin, who did not directly mention Taiwan in his remarks.

- 'Blur the lines' -

China -- which regards Taiwan as its territory and has not ruled out using force to bring it under its control -- has held four large-scale military exercises in just over two years, including the drills in response to Pelosi's visit and two since Lai took office in May.

"It can indeed be said that the scale of these maritime forces exceeds the four drills since 2022," defence ministry spokesman Sun Li-fang told reporters.

Sun said the latest exercises drew forces from three separate Chinese regional commands, while another defence ministry official said China's actions were "not solely directed at Taiwan".

There has been no public announcement by the PLA or Chinese state media about increased military activity in the East China Sea, Taiwan Strait, South China Sea or Western Pacific Ocean, where Taiwan said Chinese ships had been detected.

However, a Beijing foreign ministry spokeswoman said Tuesday that China will "resolutely defend" its sovereignty.

The lack of an announcement from Beijing was unusual and, if drills were under way, could be a "deliberate strategy to sow confusion and exert psychological pressure," Duan Dang, a Vietnam-based maritime security analyst, said.

"China's current movements resemble what we would see during preparations for real combat, exceeding the scale of previous exercises," he added.

Taipei-based security analyst J. Michael Cole said the mix of PLA navy vessels and coast guard ships highlighted Beijing's efforts to "increase interoperability" between the two.

"Such efforts also blur the lines between civilian and military components and thus complicate Taiwan's ability to respond proportionally," Cole told AFP.

- 'Confident' -

Beijing has asserted its claims over contested territories in the region far more boldly in recent years, as its military strength has grown.

The escalating actions -- over islands in the East China Sea claimed by Japan, self-ruled Taiwan, and reefs and islands in the South China Sea that are also claimed by Southeast Asian nations -- have come as Beijing's rivals have drawn closer to the United States.

Washington is Taiwan's most important backer and biggest supplier of arms, but has long maintained "strategic ambiguity" when it comes to putting boots on the ground to defend the island.

Lai said Friday he was "confident" of deeper cooperation with the next Donald Trump administration, a day after he spoke with House Speaker Johnson that angered China.

China's foreign ministry warned Taiwan on Friday that "seeking independence with the help of the United States will inevitably hit a wall", and called on Washington to "cease meddling in Taiwan-related affairs".

The dispute between Taiwan and China goes back to 1949 when Chiang Kai-shek's nationalist forces were defeated by Mao Zedong's communist fighters and fled to the island.

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