Japanese naval forces increasing activities according to the U.S. Joint Intelligence Committee. Daily summary dated 5 March 1942

An item reported that the Japanese navy seemed to increase her activities in the immediate future possible for attacking outlying Allied South Pacific possessions. Since the attack on Pearl Harbor on 7 December 1941 Japanese submarines attacked several times Allied ships although without success which could not be explained.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 85 dated 5 March 1942.