'Decanter' was the US naval contingency plan for the seizure of French Guiana (1942).

French Guiana was part of the French West Indies, which also included the Caribbean island territories of Martinique and Guadeloupe, each with its own governor. Before the outbreak of World War II, there was universal suffrage for the population of 616,000, these electing members to the local legislature, and sending representatives to the French Assembly. However, after the fall of France in June 1940 the Vichy representative, Vice-amiral d’escadre Georges Robert, whose powers extended beyond the French West Indies as far as the tiny islands of St Pierre and Miquelon off the eastern coast of Canada, suspended democracy.

The British then imposed a blockade which restricted trade with France and the USA and prevented the movement of French warships at Martinique, and also of the French gold which had been shipped there. Consequently, little food could be imported and it was difficult to export the territories' principal products, which were sugar and rum.

When it entered the war in December 1941 the USA assumed the responsibility for what was now an Allied blockade, and during March 1943 manoeuvred French Guiana into declaring for Général d’Armée Henri Honoré Giraud, the rival of Général de Brigade Charles de Gaulle for the leadership of the French liberationist movement, both to prevent the colony joining de Gaulle and the Free French, and to obtain base rights and facilities there.

Robert would not change his allegiance, however, and on 30 April the USA broke off diplomatic relations with him. Local resistance groups eventually pressured Robert into resigning on 30 June 1943, after which he was replaced by a Giraudist, himself later replaced by a Gaullist.