The Australian Protective Service (APS) was an Australian Commonwealth law enforcement agency which existed between 1984 and 2004. The APS was created by the separation of the Protective Service component of the Australian Federal Police (AFP) into a new agency based upon recommendations contained in the Stewart Royal Commission of Inquiry into Drug Trafficking. It was initially responsible for protecting personnel and property of the Australian government; foreign diplomatic missions and Internationally Protected Persons (IPPs); and the provision of custodial services at immigration detention centres. From 1990 the APS commenced providing Counter Terrorist First Response duties at certain security-designated airports including the specialist Bomb Appraisal Officer function and, following the terrorist attacks of 11 September 2001, deployed Air Security Officers (ASOs - often referred to as 'sky marshals') on board Australian registered commercial aircraft. Close Personal Protection (CPP), or bodyguard, functions were never provided by the APS; where this has been a Commonwealth responsibility, the function is provided by the AFP.