This was a US radio deception undertaking as part of 'Quickfire' in support of the 'Torch' invasion forces making the passage from the eastern seaboard of the USA direct to their North-West African assault beaches (October/8 November 1942).
The deception was designed to create the impression that the assault force which had departed Norfolk, Virginia, was bound for Syria by means of the long passage across the Atlantic Ocean via Trinidad and Recife, round the Cape of Good Hope and then to the north along the East African coast to reach Aden, the Suez Canal and thence the eastern basin of the Mediterranean Sea.
'Hotstuff' was the most elaborately implemented element of 'Quickfire'. A fictional Task Force 23 was established to conceal the real TF34, and two days before the real sailing date, the transmission of false radio traffic was started to simulate the fictional task force’s designation, organisation, assembly, routing and actual sailing, with timing arranged meticulously to allow for the notional refuelling of the escorting destroyers at sea, and fictional air and submarine coverage apparently confirmed by false messages to appropriate bases. The radio traffic peaked when the task force was at Guantanamo and San Juan on 25 October, at Trinidad on 31 October, and at Recife from 1 November. At about this last date, the British joined the effort with traffic from Freetown and Cape Town to suggest the imminent transfer of escort responsibilities to the Royal Navy.
The imaginary task force was to have reached Recife at the time the real task force reached at Casablanca on 8 November, and 'Hotstuff' was terminated at that point in a move so tactically inept that it marked 'Hotstuff' a deception to any Axis intelligence service which had followed it.
'Hotstuff' would have been implausible, of course, without corresponding radio security for the real TF34. Once this had left western Atlantic waters, its outgoing messages were routed via Gibraltar or another British station, using British procedures and codes to give the impression of emanating from a British ship. Messages to it from the London headquarters of Lieutenant General Dwight D. Eisenhower, the operation’s commander, were first cabled to Washington and then transmitted by radio from there. As TF34 approached the coast of North-West Africa, messages to it from Washington were first cabled to London and sent as British traffic, while messages from London were passed as British traffic.