Taiwan started its annual Han Kuang war games on Monday, which this year aim to be as close as possible to actual combat with no script and simulating how to repel a Chinese attack.

China, which views democratically governed Taiwan as its territory, has been staging regular exercises around the island for four years to pressure Taipei to accept Beijing's claim of sovereignty, despite Taiwan's strong objections.

Taiwan's drills this year has cancelled elements that were mostly for show, like scripted firepower displays, while there will be intensified nighttime exercises and practising how to operate with severed command lines.

Kicking off the exercises in the northern city of Taoyuan, outside of Taipei and home to Taiwan's main international airport, reservists gathered to get their orders as they would during a war, and civilian vans were pressed into service to carry supplies.

Later in the day the military will practice defending a major Taipei port.

On Thursday, Taoyuan airport will close for an hour in the morning for the drills, though a typhoon is expected to be impacting the island that day meaning that the exercise could be delayed.

Live fire drills will only take place on Taiwan's outlying islands, including Kinmen and Matsu which sit nestled next to the Chinese coast and were the scene of on-off clashes during the height of the Cold War.

The five-day war games will be happening in conjunction with the Wan'an civil defence drills, where the streets of major cities are evacuated for half an hour during a simulated Chinese missile attack, and test warning alarms will sound on mobile phones.

The drill scenarios this week include setting up contingency command lines after existing hubs are destroyed and dispersing Chinese forces trying to land on Taiwan's western coastline facing China, a defence official involved in the planning said.

China held two days of its own war games around the island shortly after President Lai Ching-te took office in May, saying it was "punishment" for his inauguration speech, which Beijing denounced as being full of separatist content.

But China has also been using grey zone warfare against Taiwan, wielding irregular tactics to exhaust a foe by keeping them continually on alert without resorting to open combat. This includes almost daily air force missions into the skies near Taiwan.

China has never renounced the use of force to bring Taiwan under its control. Lai, who says only the Taiwanese people can decide their future, has repeatedly offered talks but been rebuffed.