Beijing’s communist leaders have never renounced their claim that the island is China’s territory and have not ruled out the use of force.
And Beijing has taken an increasing hostile stance since President Tsai Ing-wen, from the pro-independence Democratic Progressive Party, won Taiwan’s elections last year.
It suspects Tsai of pushing for formal independence, a red line for China, and has held 16 rounds of military exercises close to Taiwan over the past year.
Tsai has now warned the drills are leading to mounting instability and Beijing’s military threat is growing by the day.
The president said Taiwan wanted peace but could “not have a single day without combat preparedness” and would fiercely defend the state’s security and way of life.
Tsai told senior military officers in Taipei: “In this period of time, the frequent military activities of mainland China in East Asia have already affected safety and stability in the region to a certain extent.
“Our country has always been a contributor to safety and stability in the region, this is why the national army has to keep an eye on movements of the Chinese military and take appropriate actions when needed to guarantee the safety of the country and region.”
Beijing has repeatedly claimed its drills, which have also taken place in the disputed South China Sea and the Sea of Japan, are routine and not aimed at any third party.
But it has warned Taiwan against “using weapons to refuse reunification” and its state media has given high profile to images of Chinese jets flying close to the island.
Earlier this week, China said Taiwan would have to “get used” to the “island encirclement” drills.
And tension rose this month when a senior Chinese diplomat threatened that China would invade Taiwan if any US warships made port visits there.
Taipei is well equipped with mostly US-made weapons, but has been pressing Washington to sell more advanced equipment.
The US is bound by law to provide Taiwan with the means to defend itself, much to China’s annoyance.
News of the latest war threat comes at a difficult time for US relations with China as Washington pushes Beijing to take firmer action against sabre-rattling ally North Korea.
China has also taken steps to modernise its army in recent years and announced this week that its paramilitary force, the People’s Armed Police would be brought under the control of the Central Military Commission.
The People’s Armed Police serves as a backup for the military in times of war, and domestically has a role in putting down protests and counter-terrorism as well as border defence and fire-fighting.
President Xi Jinping leads the Central Military Commission in his role as armed forces chief and commander in chief.
Xi has steadily consolidated his power over the military, and has appointed allies to key positions of power in the armed forces.
And he has radically overhauled the old Soviet-era command structure of the military to make the armed forces nimbler and better able to respond to crises at home and abroad.
That has included condensing the command structure and giving greater emphasis on new capabilities including cyberspace, electronic and information warfare.