TAIPEI (Taiwan News) — An Army major surnamed Ho (何) has been detained for allegedly spying for China in one of the most serious national security breach cases in Taiwan amid heightened cross-strait tensions.

The defense ministry confirmed on Wednesday (Aug. 9) Ho was placed in incommunicado detention for his role in handing secrets to China. His case is part of an ongoing investigation that saw an Army lieutenant colonel, surnamed Hsieh (謝), detained following raids last month.

Ho is a serving commander at the Huadong Defense Command and is said to have provided classified information to a former Army major surnamed Hsiao (蕭), who retired in April from a teaching post at the Chemical, biological, radiological and nuclear defense (CBRN) training center, reported Liberty Times.

Hsiao was questioned on July 31 and released on bail of NT$600,000 (US$18,879), reportedly because he had confessed about the source of the sensitive data he possessed.

Seven collaborators in the spying operation have been named defendants, among whom three were detained and four granted bail. The personnel ensnared in the case include serving military officers from six camps nationwide, retired officers, and civilians, per Liberty Times.

Earlier this year, Nikkei ran a series of articles alleging that up to 90% of retired military officials in Taiwan provide intelligence to China. Beijing has continued its campaign to recruit retired Taiwanese military personnel to access state secrets.