Prime Minister Tony Abbott, with Defence Minister David Johnston and chief of the Defence Force Air Chief Marshal Mark Binskin, announces the security committee's decision. Credit:Alex Ellinghausen At a press conference in Canberra on Friday with Defence Minister David Johnston and defence chief Mark Binskin, Mr Abbott confirmed cabinet had authorised the military action at the request of the Iraqi government. "I have to warn that this deployment to Iraq could be quite lengthy, certainly months rather than weeks," Mr Abbott said. "I want to reassure the Australian people that it will be as long as it needs to be, but as short as it possibly can be." The Prime Minister also warned that the mission was dangerous, but necessary to "disrupt and degrade" Islamic State "at home and abroad".

Prime Minister Tony Abbott, with Senator Johnston and Air Chief Marshal Mark Binskin, in Canberra on Friday. Credit:Alex Ellinghausen Mr Abbott said the Australian forces would have strict rules of engagement and would be involved in "advise and assist missions", helping Iraqi forces with the planning and coordination of operations. He said it was not "strictly accurate" to refer to the military engagement as a "war", because Australia was acting against an insurgency in support of the legitimate government of Iraq. Asked about the possibility of civilian casualties, the Prime Minister said it was not possible to prevent them, defence forces could only minimise the risk both to civilians and Australian personnel. "When you are conducting combat operations, you can never guarantee that there will be no collateral damage. You just can't," Mr Abbott said.

"I can say though that the Australian armed forces never ever deliberately target civilians." Mr Abbott said it was a "dangerous mission" but he was confident all possible measures have been put to place to "minimise risk". "It is an essentially humanitarian mission, yes, it is a combat deployment but it is an essentially humanitarian mission to protect the people of Iraq and ultimately the people of Australia from the murderous rage of the ISIL death cult," he said. Up to eight of Australia's Super Hornet fighters will carry out the strikes, joining bomber jets from the United States, Britain and France, all of whom have already begun air strikes. Abbott tight-lipped on Syria

The US has carried out more than 200 air strikes in Iraq and last week expanded these into neighbouring Syria. Asked whether Australia's military operations would eventually extend into Syria, the Prime Minister "counselled" against speculation about any expansion of Australia's involvement. "Let's focus on what's been done today rather than speculate on what might be done in months or years to come. We are joining combat operations as part of a US-led Coalition in support of the Iraqi government." Under the Washington-led strategy, the air strikes will be backed up by Iraqi and Kurdish fighters on the ground, who will be bolstered by training and advice by Western forces including Australia. Britain on Thursday announced it was adding a further two Tornado jets to the six fighters it already has in the region. Britain has been carrying out two air strike missions a day since Tuesday.

According to international reports, there are signs the air strike campaign has been effective, forcing a change in behaviour by Islamic State fighters, restricting their freedom of movement and stopping them from mobilising unfettered on open ground. Crucially, Turkey's Parliament late on Thursday voted to approve military action in both Iraq and Syria. The country has a large and well-equipped defence force, and feels particularly threatened by the Islamic State, which is close to taking territory in the very north of Syria close to the Turkish border. Labor backs air strikes Opposition Leader Bill Shorten said on Friday he had been briefed by the Prime Minister earlier in the day and reconfirmed Labor's support for the strikes. He said when it came to fighting terror "Labor and the government are working together".

Mr Shorten said Australia had a role to play in the global response to Islamic State. "Australians should understand these decisions are never made easily nor lightly," Mr Shorten said. "I believe the most difficult decision for a nation is the decision to send our troops in harm's way. But in the face of evil, nations of good conscience do have a responsibility to act. ISIL is not the enemy of one nation or of one faith or of one people. It is the enemy of all of us." 'Abbott blindly following the US': Greens But Greens leader Christine Milne rejected the government's assertion it was acting on a request from the Iraqi government.

"It's an incredible situation that we have now got the Iraqi ambassador saying that the Iraqi government is considering a submission from Australia to join the air strikes. That is hardly a plea from the Iraqi government that Australia participate," Senator Milne said. Senator Milne said it had been the Prime Minister's intention "from day one" to involve Australia in another Iraq war. "From day one, the PM was determined to follow the United States blindly into another war in Iraq," she said. "Before the Iraqi government had even been contacted Tony Abbott was saying we would support the United States in its effort in Iraq. "Before President Obama had even rallied his own allies, in a formal sense Tony Abbott was already there talking about the deployment of Super Hornets, talking about the deployment of Special Forces."

Fighters from the Islamic State swept from their safe-haven in neighbouring Syria – where their strength has been fuelled by the civil war – into western Iraq in January. But it was their lightning advance in June into the country's north, seizing major towns and cities including Mosul, that sent shockwaves through Western capitals and eventually prompted the international coalition – which now numbers more than 40 countries – to take action. A United Nations report released this week, based on more than 500 interviews with Iraqis, documents a "staggering array" of human rights abuses and war crimes by the Islamic State. "These include attacks directly targeting civilians and civilian infrastructure, executions and other targeted killings of civilians, abductions, rape and other forms of sexual and physical violence," the report says. It says the attacks have been "perpetrated against women and children" and include "forced recruitment of children, destruction or desecration of places of religious or cultural significance, wanton destruction and looting of property, and denial of fundamental freedoms". It says women, children, police officers, soldiers, journalists and members of minorities such as the Yazidis and Assyrians have been victims of "gross human rights abuses, at times aimed at destroying, suppressing or cleansing them from areas under their control".

Loading Nickolay Mladenov, the special representative of the UN Secretary-General for Iraq said according to the BBC: "This report is terrifying." Follow us on Twitter