Several Japanese submarines active in the Indian Ocean-Arabian Sea area according to the U.S. Joint Intelligence Committee. Daily summary dated 6 August 1942

An item reported that it seems that 4-6 Japanese submarines were active in the Indian Ocean-Arabian Sea area. The submarines were now moving eastward probably after a rendezvous with a supply ship in the Chagos Archipelago which seemed to render ineffective.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No.239 dated 6 August 1942.