Obama to press at UN for broader anti-IS coalition

US President Barack Obama plans to make his case against the Islamic State militants before the world at the United Nations General Assembly next week in a bid for greater international support in the anti-IS fight.

"We won't hesitate to take action against these terrorists in Iraq or in Syria," Obama said of the militants who have seized territory in the two neighboring countries.

"But this is not America's fight alone."

The United States is leading efforts to build a global response to the growing IS threat.

The resulting alliance has produced strange bedfellows, with Washington's traditional foe Iran represented at a meeting called by US Secretary of State John Kerry on Friday, along with US allies Britain, France, Qatar, Saudi Arabia and Turkey.

And even France, which refused to back the US-led invasion of Iraq more than a decade ago, became the first nation to join the US aerial campaign in the war-torn country as it carried out an air strike targeting the militants.

"We'll lead a broad coalition of nations who have a stake in this fight," Obama said in his weekly address on Saturday.

"This isn't America vs. ISIL. This is the people of that region vs. ISIL. It's the world vs. ISIL," he added, using another acronym by which the extremist group is known.

But despite broad support at home for a tougher stance, Obama has vowed not to send US "boots on the ground," fearful of dragging his forces back into the Iraqi quagmire only three years after withdrawing US troops from the country.

The president hailed this week's vote in Congress -- in a rare moment of unity in deeply divided Washington -- that backed his plan to arm rebels to take on IS in conjunction with air strikes due to take place inside Syria.

"Those votes sent a powerful signal to the world: Americans are united in confronting this danger," Obama said.

"And I hope Congress continues to make sure our troops get what they need to get the job done."

He counted more than 40 countries that have so far proposed to help the "broad campaign" against IS through training, equipment, humanitarian relief and air combat missions.

"And this week, at the United Nations, I'll continue to rally the world against this threat," Obama said.

He reminded Americans that "this is a moment of American leadership."

"This is an effort that America has the unique ability to lead," the president added.

"When the world is threatened; when the world needs help; it calls on America. And we call on our troops."