The exercises were also in response to Beijing's army restricting the airspace off the Chinese coast.

"In response to these actions by the PLA, the MND has initiated combat readiness drills, factoring in enemy threats, weather conditions, and tactical positioning," the defence ministry said in a statement, adding that military units were on "high" alert.

There has been intense speculation about the possibility of China launching military drills in response to Taiwan President Lai Ching-te's Pacific tour last week that included two stopovers on US soil.

The ministry said on X its forces had "identified PLA Eastern, Northern, and Southern Theater Command naval formations, along with Coast Guard vessels, entering areas around the Taiwan Strait and the Western Pacific."

There was no immediate public announcement by the PLA or Chinese state media about increased military activity around Taiwan.

While Taiwan regards itself as a sovereign nation -- with its own government, military, and currency -- Beijing insists the island is part of its territory and has not ruled out using force to bring it under its control.

In Guam on Thursday, Lai spoke with Republican US House Speaker Mike Johnson -- the highest-level US contact the Taiwanese leader had during his week-long trip -- which drew a barrage of criticism from Beijing.

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".

In response to a question about possible Chinese military drills around Taiwan following his trip, Lai told reporters on Friday that "raising your fists is not as good as opening your hands".

"No matter how many military exercises, warships and aircraft China sends to coerce neighbouring countries, it cannot win the respect of any country," Lai said.

- 'Unusual movements' -

Taiwan's coast guard said Monday it had detected "unusual movements" of seven Chinese coast guard ships since early Friday -- the day Lai returned to Taipei.

Lai's tour -- his first overseas trip since taking office in May -- was aimed at fortifying ties in the Pacific where China has been poaching Taiwan's allies.

Taiwan faces the constant threat of a military attack by China and relies heavily on US arms sales to boost its defences.

On the eve of Lai's Pacific tour, the United States approved a proposed sale to Taiwan of spare parts for F-16s and radar systems, as well as communications equipment, in deals valued at $385 million in total.

Speaking in the US state of Hawaii during his trip, Lai said there was a need to "fight together to prevent war", warning there were "no winners" from conflict.

China has launched two large-scale military drills around Taiwan since Lai took office and regularly deploys fighter jets and navy ships to press its claims over the island.

Lai has been more outspoken than his predecessor Tsai Ing-wen in defending Taiwan's sovereignty, angering Beijing which calls him a "separatist".