TAIPEI — Taiwan's capital Taipei came to a standstill on Thursday as the island held one of its largest-ever civil defence exercises against possible Chinese invasion.

Air raid sirens rang out across the metropolitan area and in some areas residents sought shelter indoors, while traffic ground to a halt. The city also held mass evacuation drills and mass casualty event rehearsals.

The exercise was held in conjunction with Taiwan's largest ever war games - the annual Han Kuang exercises - as the island increasingly attempts to ramp up its defences.

China claims self-ruled Taiwan as its part of its territory and has not ruled out the use of force to "reunify" with the island.

Tensions have increased since last year when Taiwan elected its president William Lai, whom China reviles as a "separatist".

Thursday's event was attended by Lai, government and city officials, and foreign officials including Raymond Greene, the head of the American Institute of Taiwan which serves as a de facto US embassy on the island.

In a speech at the end of the exercise, Lai stressed the importance of unity and resilience of Taiwan's society to protect the island and its democratic values.

He also stressed that the Han Kuang and Urban Resilience exercises were aimed at building up Taiwan's defences and that the island was not seeking war.

"We hope by preparing for war, we can avoid war, to achieve the goal of peace," he said. "With preparation, we have strength."

China has criticised the exercises as "a bluff and self-deceiving stance" by Lai and his ruling Democratic Progressive Party aimed at pushing a pro-independence agenda.

While previous Han Kuang exercises also had civil defence components, this year authorities have combined them in a single Urban Resilience exercise across the island which began on Tuesday and ends on Friday.

Each day of the exercise sees air raid sirens ringing out for half an hour in several cities.

Residents in designated areas in each city must shelter indoors or risk incurring a fine. All shops and restaurants must also pause operations. Road traffic must also come to a stop, with drivers required to pull over and head indoors immediately.

In Taipei, hundreds of emergency workers and volunteers took part in air raid drills and evacuations at a busy temple square, schools, subway stations and highways.

They also held a mock mass casualty event simulating missile or bomb strikes on buildings, where emergency personnel pulled out survivors and treated their injuries, and set up distribution points for emergency supplies.

This week's Urban Resilience exercise is the latest civil defence drill Taiwan has held this year as it tries to prepare its cities for possible attacks and raise its population's defence awareness.

While US officials have warned of an imminent threat from China and that President Xi Jinping wants his military to be capable of invading Taiwan by 2027, most Taiwanese remain sceptical that an actual invasion will take place.

One poll done last October by a government-linked think tank, the Institute for National Defence and Security Research (INDSR), found that more than 60% of Taiwanese do not believe China will invade in the next five years.

"The chances of China invading are low. If they really wanted to invade us, they would have done it long ago," said Ben, a 29-year-old finance professional interviewed by the BBC in Taipei on Wednesday.

"But I do believe we need these drills, every country needs it and you need to practise your defence... I believe there is still a threat from China."

Others were more sceptical.

"There is just too big a difference in the strengths of China and Taiwan's militaries," said Mr Xue, a 48-year-old office worker. "There is no use defending ourselves against an attack."

The IDSR poll had found that only half of Taiwan's population had confidence in their armed forces' capability to defend the island.

It is a long-running sentiment that has spurred the Taiwanese government in recent years to beef up its military and expand Han Kuang.

More than 22,000 soldiers - about 50% more than last year – rehearsed defending the island from potential attacks from China in land, sea and air drills.

Newly acquired military hardware such as the US-supplied Himars mobile missile system as well as Taiwan-made rockets were tested.

This year's Han Kuang exercise also focused on combating greyzone warfare and misinformation from China, as well as rehearsing military defence in cities.

In recent days soldiers took part in urban warfare exercises in an exhibition centre and on the subway in Taipei.

On Thursday morning at a riverside park in a Taipei suburb, troops practised re-fueling and re-arming Black Hawk and Apache helicopters with Hellfire and Stinger missiles supplied by the US.

The day before the military rehearsed pushing back enemy troops on the streets of Taichung city, and turned a high school in Taoyuan into a battle tank repair station. — BBC