Mr Kao is the highest-ranking veteran of Taiwan’s armed forces to have been accused of spying for China, but he is not the first. In January another group of veterans was indicted for allegedly sending photos and maps of America’s de facto embassy in Taipei and of Taiwanese military bases to Chinese agents.

The UK’s engagement with Taiwan and China should not be a matter of choosing one side or the other, and maintaining relations with China does not mean it cannot have a fruitful relationship with Taiwan, British Member of Parliament (MP) Sarah Champion said in an interview.

The tension between China and Taiwan is at its highest. In China's eyes, Taiwan is a breakaway province that they need to reconquer. However, Taiwan sees itself as its own independent state from China.