At least 62 active-duty Taiwanese military members have been found holding Chinese residency permits, in the latest revelation of Chinese influence in the Taiwanese armed forces.

Since splitting amid civil war in 1949, China has considered Taiwan a renegade province and increasingly relied on “gray area” tactics to undermine Taiwan’s will to resist on top of its threat of a military invasion.

Such residency permits give the holder the right to reside in China, potentially an option in case of an outbreak of hostilities. China, which does not recognize Taiwan passports, also issues a special document allowing Taiwanese to visit the mainland.

Holding such documents is legal in Taiwan, but can affect access to sensitive information. The 62 active-duty service members will be barred from handling intelligence and confidential data, Defense Minister Wellington Koo told a legislative hearing on Wednesday.