Sources say a serving Japanese defense ministry official has been dispatched to Taiwan and stationed within an organization that serves as a liaison with Japan.
The move reflects Japan's heightened efforts to gather intelligence in response to mounting concerns about a potential crisis in Taiwan.
Japan has no diplomatic ties with Taiwan. Instead, the Taipei office of the Japan-Taiwan Exchange Association acts as Japan's de facto Embassy. Various Japanese officials, including those from the foreign ministry and the economy and industry ministry, are posted there.
Sources close to the matter say a civilian bureaucrat from the defense ministry has been stationed in the Taipei office since this spring.
Until then, the defense ministry had not dispatched any serving officials to the organization.
A retired Japanese Self-Defense Forces officer has been assigned there since 2003, bringing the total number of Japanese officials in charge of security to two.
Still, Japan has refrained from dispatching a serving SDF officer to Taiwan, unlike some other nations that have no diplomatic ties with Taiwan but station uniformed officers there.
Observers suggest that Japan has avoided doing so to prevent provoking China, which claims Taiwan as its own.