US President Barack Obama addresses Islamic State threat

US President Barack Obama says he is ready to launch air strikes on Islamic State fighters in Syria, expanding the campaign already undertaken against the jihadists in Iraq.

"I have made it clear that we will hunt down terrorists who threaten our country, wherever they are. That means I will not hesitate to take action against IS in Syria, as well as Iraq," Obama said in a televised address.

"This is a core principle of my presidency: if you threaten America, you will find no safe haven."

"Our objective is clear: we will degrade, and ultimately destroy, IS through a comprehensive and sustained counterterrorism strategy.”

US President Barack Obama delivers a live televised address to the nation on his plans for military action against the Islamic State from the Cross Hall of the White House in Washington. Photo: REUTERS/Saul Loeb

• US wants Australian special forces to fight jihadists

• In Syria, Obama must win trust to beat Islamic State

He called on Congress to give him "additional authorities and resources to train and equip" the Syrian opposition, saying they were the "best counterweight" to IS fighters, who have seized wide swaths of territory in Iraq and Syria.

"In the fight against IS, we cannot rely on an Assad regime that terrorises its people; a regime that will never regain the legitimacy it has lost," he said, referring to Syrian President Bashar al-Assad.

Obama said the United States would lead a "broad coalition" to roll back the threat posed by IS, but insisted that US combat troops will not be sent to fight on foreign soil as part of the operation.

“I want the American people to understand how this effort will be different from the wars in Iraq and Afghanistan," Obama said.

"It will not involve American combat troops fighting on foreign soil. This counterterrorism campaign will be waged through a steady, relentless effort to take out ISIL wherever they exist using our air power and our support for partner forces on the ground. This strategy of taking out terrorists who threaten us, while supporting partners on the front lines, is one that we have successfully pursued in Yemen and Somalia for years.”

Obama delivered a prime-time speech to lay out his plan for “degrading and ultimately destroying the terrorist group” known as the Islamic State, which has left a trail of carnage as it pushed out of Syria and across Iraq.

During the legacy-defining address, Obama delivered a progress report of sorts on the more than 150 US airstrikes against IS since early August, a campaign that has checked the group’s fearsome advance into Kurdish territory and towards Baghdad.

He also detailed his efforts to rally a coalition of Western and Muslim nations behind military action against IS, as well as his proposals for shoring up Syrian rebels from factions less extreme than IS but as dedicated to strongman Bashar Assad’s ouster.

The escalation puts the president elected to pull America from its painful overseas military entanglements, notably the Iraq War, in the position of plunging the United States into a new Middle East conflict that could outlast his presidency and cost untold amounts of American blood and treasure.

It comes amid reports from The West Australian that the US wants Australia to commit special forces soldiers to an international mission to destroy IS militants rampaging through northern Iraq.Australia has already indicated it would offer jet fighters to a US-led coalition but The West Australian understands that Washington believes Australia's most valuable contribution to the mission would be Special Air Service Regiment troops and Commandos.

Call to arms: US wants Australian Special Forces to join the fight. Photo: ADF

Senior Government figures say the US has high regard for the logistical and "disruption" abilities of Australian special forces.The National Security Committee will decide the strength and shape of Australia's contribution soon after Obama's address.He called Saudi King Abdullah, a pivotal member of the coalition he is building to battle IS, and gathered top defence and intelligence chiefs, while finalising a strategy for the kind of prolonged new intervention in the Middle East he has always abhorred.

US President Barack Obama speaks on the phone to Saudi Arabia's King Abdullah from his desk at the White House in Washington ahead of his address regarding Iraq and Islamic State group militants. Photo: AP/Charles Dharapak

Officials said Obama was also pressing Congress to sign off on $500 million in aid to equip and train "moderate" Syrian rebels, who would be on-the-ground partners for any US air campaign.The complex blend of forces opposed to both President Bashar al-Assad and IS was, meanwhile, scrambled again by a bomb blast which killed nearly 50 members of the leadership of the Islamist Ahrar al-Sham faction.

Islamic State militants pose with the trademark jihadist flag after they allegedly seized an Iraqi army checkpoint in the northern province of Salahuddin. Photo: AP

In Iraq, meanwhile, Secretary of State John Kerry promised that Iraq's armed forces, some of which turned tail and fled the IS advance, would be "reconstituted and trained and worked on."The plan would not just be a US effort but also involve US partners, Kerry said.

Protestors call on President Barack Obama to help end the bloodshed of Iraqi Christians as hundreds demonstrate against the terrorist group IS in Sterling Heights, Michigan. Photo: AP Photo/Detroit News/Brandy Baker

NEW LEADERSObama has repeatedly told Americans, that after "ending" the US war in Iraq to honour a key campaign promise, he will not send US ground troops back into combat in the country.But he has not ruled out sending US trainers to help prepare Iraqi forces -- stood up at the cost of billions of US taxpayer dollars after the 2003 US invasion.Kerry praised the new Iraqi government of Prime Minister Haidar al-Abadi, which Washington says has the potential to offer the "inclusive" rule across sectarian divides that the former administration of Nuri al-Maliki failed to provide.

But the complex sectarian stew facing Abadi was underlined when bombs killed 19 people in east Baghdad during Kerry's visit.Ahrar al-Sham quickly named new leaders to replace those killed in a blast at a meeting of its top religious and military chiefs in the northeastern Syrian province of Idlib.The group, which espouses a conservative ideology despite not backing IS, had been seen as a bridge between more moderate and radical streams of the opposition.Analysts said the attack threatened the cohesion of the Islamic Front opposition coalition but it was unclear if the attack could benefit Islamic State or Assad's forces.

The Islamic State group holds roughly a third of Iraq and Syria, including several strategically important cities like Fallujah and Mosul in Iraq and Raqqa in Syria. Photo: AP

POIGNANTObama won power on an anti-Iraq war platform, and has devoted much of his presidency to avoiding new long-term entanglements in the Middle East -- notably avoiding getting bogged down in Syria and in Libya after leading a coalition to overthrowBut the plan he laid out on Thursday will lack a definitive end date -- and the campaign could outlast his own presidency, which ends in January 2017."I think the American people need to expect that this is something that will require a sustained commitment," said White House spokesman Josh Earnest.

The address has come at a poignant time -- on the eve of the 13th anniversary of the September 11 attacks, when Islamic radicalism on a mass scale scorched the US homeland for the first time.Obama, who has seen his personal approval ratings and public confidence in his foreign policy ebb during a series of domestic and international crises, at least appears to have popular opinion on his side on Syria.A new Wall Street Journal/NBC News poll suggested the US public was increasingly hawkish about IS, with two-thirds of those asked backing military operations against the group.Opinion surveys also suggest that Americans share Obama's skepticism on deploying ground troops in Iraq.The White House insists that IS, despite beheading two US journalists, does not yet pose an imminent threat to the US homeland.

Islamic State militants called American journalist James Foley’s gruesome videotaped beheading revenge for US airstrikes against the group, and they still hold at least two other Americans hostage. Photo: AP

But they worry the group could eventually send some of its legions of foreign fighters armed with Western passports, to stage attacks in America.The President previewed his speech in a meeting with top congressional leaders on Tuesday, then Wednesday huddled with defence and intelligence chiefs in the White House Situation Room.

Officials said he made clear that he believes he has sufficient authority to carry out his new strategy without asking Congress for a new war authorisation.Mitch McConnell, the Republican Senate minority leader however warned that to win broad support, Obama must show bold leadership and not just restate existing policy."If Congress is asked to support a strategy, it needs to be a strategy that is designed to succeed," he said.