TAICHUNG: Taiwan unveiled a new locally-built training jet on Monday, a boost for the island's push to manufacture its own defence weapons as it faces off against an increasingly belligerent China.

President Tsai Ing-wen attended a ceremony for the first public flight of the "Brave Eagle" Advanced Jet Trainer (AJT), describing it as a "historic moment". "Today is a big day for the Republic of China air force and it's also an important landmark for the domestic aerospace industry," Tsai told a crowd in central Taichung, using Taiwan's official name. "This is a critical part of realising our defence self-sufficiency."

Trainers are what pilots learn on before switching to much more expensive fighter jets and the AJT will allow Taiwan to replace its current fleet of obsolete aircraft.

Democratic Taiwan lives with the constant threat of invasion by China which views the self-ruled island as part of its territory and has vowed to one day seize it, by force if necessary.

In recent decades it has found itself out-numbered and out-gunned by China's enormous People's Liberation Army.

The imbalance has been compounded by western governments becoming increasingly wary of selling it advanced weapon systems, fearful of incurring Beijing's wrath.

That has pushed Taiwan to develop its own hardware, including advanced missiles, boats and the new trainer jet.

Beijing has ramped up military, diplomatic and economic pressure since Tsai first took office in 2016 as she has refused to acknowledge that Taiwan is part of "one China".

She won a landslide reelection in January in what was seen as a strong rebuke to China's hardline campaign against the island.