In December 1941, due to concerns about a Japanese invasion, the Dutch requested that Australian forces be sent to both Koepang and Ambon under provisions that had been agreed to in a conference at Singapore earlier in the year. That plan, entitled "Plans for the employment of naval and air forces of the associated powers in the eastern theatre in the event of war with Japan" (Plenaps), had already resulted in the disposition of forces, including some U.S. fleet movements, as early as November 1941. Initially, Australian plans were to send forces only to Koepang with the resulting order to embark the force at Darwin, designated "Sparrow," on 7 December 1941 using the transport and the armed cruiser HMAS "Westralia", which were available in the port. The decision to exclude Ambon was quickly changed with 1,090 troops designated "Gull Force" sent to Ambon from Darwin on 14 December using three Dutch merchant ships.