Australian police have issued arrest warrants for two Sydney men accused of fighting with terrorist groups in Iraq and Syria.
Khaled Sharrouf and Mohamed Elomar recently posted images from Iraq on Twitter, showing them posing with the heads of executed fighters, holding guns and standing over bloodied bodies.
In other online posts, they threatened to kill Australian soldiers and all non-Muslims.
Attorney-General George Brandis described the Australians who have joined ISIL as the biggest threat to Australian national security.
"What they have demonstrated is a promotion of violent crimes, probably war crimes," Attorney-General George Brandis told the ABC's 7:30.
A spokeswoman for the Australian Federal Police said the pair would be arrested immediately for terrorism-related offences if they returned to Australia.
However, a friend of the pair told Fairfax Media they have no intention of ever returning.
"They say they've never lived a better life than what they’re living now and 'you don't know what youse are missing out on, especially with the turn of events happening now [with the establishment of a caliphate in Iraq]," said the friend, who didn't want to be identified.
"People say they're worried these guys will come back but they understand that if they leave the country to go to Syria or Iraq they're not coming back. They're after two things - victory for Islam or martyrdom."
But the Attorney-General emphasised that home-grown terrorism remains a significant domestic threat.
He will seek to introduce legislation to parliament to make it an offence to encourage terrorism.
"One thing no one should think is that this is a problem on the other side of the world," said Brandis. "This is a problem that exists and germinates within our suburbs."
It is believed Sharrouf and Elomar left Australia last year to fight in Syria and crossed over to Iraq when conflict broke out.
Last week, they posted photos of themselves holding up the severed heads of fighters.
It followed a series of graphic and provocative photos from the Iraqi battlefield and various threats of violence.
It's believed Sharrouf and Elomar are fighting with al-Qaeda-linked rebel group Islamic State of Iraq and the Levant, which is classified in Australia as a a terrorist organisation.
Elomar's Sydney wife and the mother of his four children, Fatima, was recently charged with supporting terrorism under foreign incursion laws.
She was allegedly stopped at Sydney Airport on May 3 with cash and military fatigues.
Her lawyer, Zali Burrows, said on Tuesday that the arrest warrants for terrorism were not a surprise, considering Elomar's wife had already been charged with supporting a terrorist.
She cast serious doubt on the veracity of the Twitter posts, saying neither Sharrouf nor Elomar use the social network. She believes the photo of Elomar with severed heads may have been photoshopped.
An AFP spokeswoman said: "As these matters are ongoing, and yet to be tested before a court, it would not be appropriate for the AFP to comment further," the spokeswoman said.
"Should Sharrouf or Elomar return to Australia, these warrants authorise law enforcement to arrest them immediately."
“We would be alleging that they were members of a terrorist organisation.”
- Sydney Morning Herald