Fighter jets practised landing on a highway in southern Taiwan on Wednesday as part of an annual live-fire military exercise that simulates defending the island against an invasion by China.

Democratic Taiwan lives under constant threat of invasion by Beijing, which claims the island as part of its territory and has vowed to one day seize it, by force if necessary.

A US-made F16 fighter jet takes off from a motorway in Pingtung, southern Taiwan
A US-made F16 fighter jet takes off from a motorway in Pingtung, southern Taiwan AFP / Sam Yeh

Military tensions have risen to their highest in decades under President Xi Jinping with China now routinely sending fighter jets and nuclear capable bombers into Taiwan's air defence zone and state media regularly publicising invasion drills.

On Wednesday morning, various Taiwanese fighter jets as well as an early warning aircraft practised taking off and landing on a provincial highway in Pingtung county.

The drill, which was watched by President Tsai Ing-wen, is supposed to hone Taiwanese pilot skills if the island's airstrips are wiped out.

Taiwanese airforce fighter jets and an E-2K Early Warning Aircraft land and take off on a motorway in an exercise simulating a mock attack by enemies destroying their airbase. The military exercise is part of Taiwan's annual live-fire war games to prepare
Taiwanese airforce fighter jets and an E-2K Early Warning Aircraft land and take off on a motorway in an exercise simulating a mock attack by enemies destroying their airbase. The military exercise is part of Taiwan's annual live-fire war games to prepare itself against a potential Chinese invasion. AFPTV / Sean CHANG

"Such excellent combat skills, precise and swift movements come from rigorous training and demonstrate the air force's confidence to protect our airspace," Tsai said in a post on her Facebook.

Part of its annual Han Kuang military exercises, Wednesday's drill took place on one of five highways that have been deliberately built with long sections that can accommodate planes landing.

An E2K early warning aircraft also took part in the drill using a road as a runway
An E2K early warning aircraft also took part in the drill using a road as a runway AFP / Sam Yeh

An invasion of Taiwan would be a hugely costly and difficult endeavour but Beijing has increasingly closed the military gap in recent years and Xi has made no secret of his desire to see the island taken.

Senior US generals have publicly warned that China could potentially carry off an invasion and the defence of Taiwan has become a rare bipartisan issue in Washington.

Last year Chinese jets and bombers made a record 380 incursions into Taiwan's air defence identification zone (ADIZ).

The number of incursions for the first eight months of this year has already exceeded 400.

In June, 28 Chinese jets breached Taiwan's ADIZ in the largest single-day incursion. That came shortly after G7 leaders issued a landmark statement urging peace in the Taiwan Strait.

Taiwan's ageing fighter fleet has suffered a string of fatal accidents in recent years as its air force is kept under constant pressure by China.