Taiwan raised its alert level on Monday saying China has set up seven zones of reserved airspace and deployed naval fleets and coast guard boats in what a security source described as the first military drills across a broad swathe of the region's waters.

A senior Taiwan security official told Reuters that China currently has nearly 90 navy and coast guard ships in waters near Taiwan, the southern Japanese islands and the East and South China Seas, of which around two-thirds were navy vessels.

Beijing’s defence ministry did not immediately respond to a Reuters request for comment.

China, which claims democratically governed Taiwan as its own territory, had been expected to launch another round of exercises in response to Taiwan President Lai Ching-te’s trip to the Pacific, which included stopovers in Hawaii and the US territory of Guam, security sources had told Reuters.

China has set up seven “temporary reserved areas” of airspace to the east of its eastern Fujian and Zhejiang provinces, Taiwan’s defence ministry said in a statement, adding those zones are valid from Monday to Wednesday.

Such zones are temporarily reserved and allocated for a particular user during a set period, though other flights can pass through with permission from controllers, according to international rules.

In Washington, the White House did not immediately respond to a request for comment.

The Taiwan security official, speaking on the condition of anonymity, said the scale of China’s navy and coast guard deployment was larger than the previous two major drills around Taiwan this year, which were dubbed “Joint Sword 2024-A” and “Joint Sword 2024-B”.

“For the first time they are targeting the entire island chain,” the source said, referring to an area that runs from Japan through Taiwan, the Philippines and onto Borneo, enclosing China’s coastal seas.

"They are meant to achieve total military intimidation by positioning to control the inner part of the island chain."

Taiwan’s military said it has activated its “combat readiness exercises” at strategic locations and its naval and coast guard boats are closely monitoring Chinese military activities.

“Any unilateral and irrational, provocative actions could seriously damage peace and stability in the Indo-Pacific and that will not be welcomed by the international community,” Taiwan’s defence ministry said.

‘Grey Zone Harassment’

The reason behind China's reserved airspace zones was still unclear, said Wang Ting-yu, a senior lawmaker for Taiwan's ruling Democratic Progressive Party.

"They are likely to run military activities, or it's only just a false alarm meant to exert political pressures," said Wang, who leads the parliament's defence and foreign affairs committee.

“Please be a civilized neighbouring country. Don't be a troublemaker all the time.”

Taiwan's coast guard, in a separate statement, said that seven Chinese coast guard ships have been carrying out “grey-zone harassment” against the island since earlier in the day.

China does not have the right to carry out any intrusion or law enforcement actions in Taiwan’s waters, and Taipei has the right to take necessary measures in response, the coast guard said.

Taipei says China has been using “grey-zone” tactics that stop short of actual combat to test and pressure Taiwanese forces, including daily air force and navy missions around the island and regular coast guard patrols.

Beijing detests Lai as a “separatist” and has rebuffed his repeated calls for talks. Lai and his government reject Beijing’s sovereignty claims, saying only Taiwan’s people can decide their future.

China’s sabre rattling around Taiwan, as well as in the disputed South China Sea, has raised fears of possible conflict.

US Defense Secretary Lloyd Austin, speaking to US sailors at the Yokosuka naval base in Japan on Monday, said China is the only country in the world that has the intent and increasingly the capability to change the rules-based international order.

“And so we want to see this region, this area remain open to freedom of navigation and the ability to fly the skies and international airways whenever we want to,” he added.