The War on Terror raged relentlessly in Australian minds in 2004.
Three years after 9/11 and two years after the Bali bombings, Australians were again threatened by the spectre of Islamist terrorism, previously unseen cabinet documents declassified on Wednesday show.
With al-Qaeda still at large in the Middle East and flexing its strength through a wave of suicide bombings in 2004, officials contemplated how to respond to a September 11-style attack on Australian soil.
If they believed a plane was involved in a suicide attack, the prime minister or defence minister could at any time direct the defence force to shoot it down, a cabinet memorandum noted.
The government has "executive power under section 61 of the constitution (to) order the chief of the defence force to utilise the Australian Defence Force to protect a 'Commonwealth interest'" and down an aircraft if necessary, the document states.
But officials noted even if that power was used, defence did not have forces at sufficient readiness to respond to a suicide plane attack at short notice.
Australia's limited radar coverage and communication with aircraft would further affect response times, and even a streamlined decision-making process would unlikely be fast enough to prevent an attack.
"It is conceivable that a hijacked aircraft flying near Sydney, for example, may be on its legitimate flight path until the last 30 seconds of its flight," the document said.
Cabinet noted mitigating measures had already been undertaken to prevent plane hijackings, including air security officers and hardened cockpit doors.
Disaster was narrowly avoided in March 2002 when the RAAF came perilously close to sending a fully-armed F/A-18 Hornet to shoot down a light plane.
The aircraft was detected flying towards restricted airspace where world leaders were gathering at the Commonwealth Heads Of Government Meeting on the Sunshine Coast, before changing course at the last minute.
Australia has thankfully been spared from such incidents, but the nation was shaken by a terrorist attack in September 2004 when a one-tonne car bomb detonated outside the Australian embassy in Jakarta, killing 10 people.
While no Australians working at the embassy were killed, aftershocks resonated through the government.
Officials scrambled to upgrade security arrangements at embassies and consulates around the world, according to minutes of a National Security Committee meeting in the wake of the bombing.
Cabinet agreed to blast-proof windows at all Australian diplomatic missions given the high risk of politically motivated violence.
Relocating Australia's Jakarta embassy and Bali consulate were high priorities given the ongoing threat of Islamist group Jemaah Islamiah, which had claimed responsibility for the Bali and Jakarta embassy bombings.
Amid escalating sectarian conflict in the wake of the 2003 US-led invasion of Iraq to topple Saddam Hussein, concerns were also heightened around the security of Australia's embassy in the capital Baghdad.
A "campaign of violence" by terrorist insurgents was undermining Iraq's reconstruction process and ratcheting fears for the safety of Australian troops and civilian advisers.
"Australia's engagement strategy is based on the assumption that Australian nationals will be targeted by insurgents, including possible kidnapping," a briefing submitted by then-foreign minister Alexander Downer said.
