India, Oct. 18 -- Taiwan is both a frontline of Beijing's geopolitical contest and a hub for Tibetan diaspora activism.

The story of a woman on pilgrimage to Mount Kailash in Tibet being stopped at a checkpoint and confronted with photographs of her participation in the Central Tibetan Administration's (CTA) representative house in Taipei is more than an isolated incident. It is a window into the quiet but pervasive reach of Chinese intelligence operations in Taiwan.

Chinese intelligence has long relied on a mix of overt and covert tactics to monitor Tibetan exile communities. What is striking here is the precision: the woman was shown images of her presence at a CTA reception in Taipei, a space meant to symbolize cultural resilience an...