Islamic State hacked Australians 
Australia has been discussing with the United States and other allies the prospect of expanding RAAF bombing raids against the Islamic State terror group into Syria and is likely at some stage to commit to the expansion, Fairfax Media understands.
Liberal MP Dan Tehan, who chairs a high-powered parliamentary committee on intelligence and security, put the issue squarely on the radar on Thursday by issuing a call for Australian planes to expand strikes from Iraq to neighbouring Syria. 
Labor quickly signalled it is unlikely to support expanding bombing raids into Syria, threatening what has until now been a major-party consensus on the fight against the Islamic State.
Prime Minister Tony Abbott has never ruled out extending air strikes from Iraq into Syria. Fairfax Media understands Australia has had ongoing conversations with the US about the RAAF's potential involvement in bombing raids in Syria.
While no decision has yet been made, and may not be made for some time, Fairfax Media has been told it is likely a matter of "when not if".
The US, Canada, Britain and a number of Arab countries are already bombing Islamic State targets in Syria, where the terror group has its defacto capital and where it holds much of its territory.
Labor deputy leader and foreign affairs spokeswoman Tanya Plibersek said on Thursday morning there was no legal basis for Australian air strikes in Syria and added that Mr Abbott himself had made the same point in the past.
"As the Prime Minister himself has said, there is no clear legal basis for Australian involvement in Syria," Ms Plibersek told reporters in Canberra.
"And there is no clarity about the outcome that Australia would be fighting for. On the one hand we've got IS. On the other hand we've got the Assad regime and we've got hundreds of groups proliferating in Syria.
"If the Prime Minister believes that Australia should be involved in Syria, he should come into the Parliament, he should explain the basis on which he's changed his mind and he should make a case to the Australian people through the Australian Parliament.
"It is extraordinary to be sending a backbencher out to run up the flagpole a decision as serious that would send Australian armed personnel into harm's way in one of the most dangerous places in the world."
By contrast, there was "a very clear legal basis for Australian involvement in Iraq" because the government in Baghdad has invited the Australian Defence Force to help with the fight against the Islamic State, Ms Plibersek said.
But Fairfax Media understands that any expansion is likely to target Islamic State supply lines between Syria and Iraq, rather than taking RAAF planes deep into the heart of the terror group's territory.
The legal basis would therefore be that the threat posed by Islamic State in Iraq is emanating from neighbouring Syria, justifying crossing the border to tackle that threat.
The RAAF has been carrying out strikes in Iraq since late last year as part of an international campaign. It is currently flying six Hornet fighter planes as well as an aerial refueller and a radar command and control aircraft.
It is understood that discussions have revolved around stretching the existing RAAF planes' missions rather than sending additional aircraft and personnel.
Mr Tehan told the ABC that "if necessary, we could look at putting additional aircraft on".
"It's in our national interest to do so. We have foreign fighters from Australia still going to the caliphate. Some of them, history shows, will try and return home and carry out terrorist attacks here."
Mr Tehan said he had not spoken to Mr Abbott about the issue. Rather, after a recent overseas trip on which he spoke with US and European officials, he had "come firmly to believe in" an air strike expansion.
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