Just hours after a video purported to show the beheading of British aid worker David Haines was aired, Australia said it will deploy at least 600 military personnel in Iraq to fight Isis.
Prime Minister Tony Abbott said he will be sending the troops at US request and the first set of 200 troops will arrive in the UAE within the next few days.
Calling the beheading of Haines as "Shock, horror, outrage, fury," he said, up to eight Super Hornet aircraft will also be sent to Iraq in order assist the international effort against the Sunni insurgent group.
"Again I stress that this is essentially a humanitarian operation to protect millions of people in Iraq from the murderous rage of the ISIL movement," he said.
"Again I stress that this movement is neither Islamic nor a state. It is a death cult reaching out to countries such as Australia. This is about taking prudent and proportionate action to protect our country and to protect the wider world against an unprecedented terrorist threat."
While about 400 personnel will be drawn from the Royal Australian Air Force (RAAF), 200 troops will be drafted from the army.
Stating that the campaign would be a long drawn out one, Abbot said: "I have to warn the Australian people that should this preparation and deployment extend into combat operations, this could go on for quite some time — months rather than weeks, perhaps many, many months indeed."
He said he was not aware of any Australians being held hostage by Isis jihadists in Iraq or Syria.
The Australian cabinet and the National Security Committee had earlier held sessions to discuss the latest deployment proposal.