Special Operations Australia (SOA), a joint Allied military intelligence organisation, was established in March 1942. SOA operated under the cover name Inter-Allied Services Department (IASD). It contained several British SOE officers who had escaped from Japanese occupied Singapore, and they formed the nucleus of the IASD, which was based in Melbourne. In June 1942, a commando arm was organised as Z Special Unit (which was later commonly known as Z Force). It drew its personnel primarily from the Australian Army and Royal Australian Navy.