British merchant ships Proteus and Nereos still not arrived according to the U.S. Joint Intelligence Committee. Daily summary dated 23 December 1941

An item reported that the non-arrival at Portland, Maine, USA by the British merchant ships Proteus and Nereos due 28 November and 16 December was possible caused by sabotage. Both ships were loaded with bauxite from St. Thomas. While there was no information available about an enemy raider of extensive submarine activities sabotage seemed the most reasonable explanation.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 13 dated 23 December 1941.