NAPSNet – This is a study of Japan’s ground-based signals intelligence (SIGINT) stations, the 17 (soon to be 19) major facilities that intercept, monitor, collect, process and analyse foreign electronic signals. Official statements convey nothing of the scale or detail of the Japanese SIGINT effort, which is probably the third or fourth largest SIGINT establishment in the world. These Japanese ground signals interception and location facilities are integrated with its air and missile defence radar facilities. Together with Japan’s own long-range underwater surveillance systems, and combined with the Japan-based US parallel air, ground and underwater surveillance systems, they take Japan a very long way towards its stated aim to ensure information supremacy in the region. As potentially lucrative targets in the event of war, destruction of these important but vulnerable facilities could alter escalation dynamics in such a way that the widespread assumption that a Japan-China armed conflict could be controlled before substantial escalation may not hold true.