Japanese Naval Intelligence service collecting details about US Pacific convoys according to the U.S. Joint Intelligence Committee. Daily summary dated 24 March 1942

An item reported that the Japanese Naval Intelligence service at Tokyo seemed to acquire details of US convoys towards the Pacific shortly after their departure.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 104 dated 24 March 1942