Japanese warships probably gathering in the Bonin Islands according to the U.S. Joint Intelligence Committee. Daily summary dated 18 March 1942

An item reported that most of the Japanese naval vessels mentioned in Summary No. 94 and part of the screening force were believed to be concentrated in the Bonin Islands.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 98 dated 18 March 1942.