France's president has said there is "no time to lose" in the global push to combat extremists from the Islamic State group, as reconnaissance planes from his country stand ready for action.
With memories of the 2003 invasion of Iraq still fresh, the US has so far been alone in carrying out airstrikes and no country has offered ground troops.
But French reconnaissance jets were prepared to take off today, a French official said. An American official said several Arab countries had offered to conduct airstrikes.
"The terrorist threat is global and the response must be global," President Francois Hollande said, opening an international conference intended to come up with a global strategy against the group. "There is no time to lose."
Muslim-majority countries are considered vital to any operation to prevent the militants from gaining more territory in Iraq and Syria.
But there are issues over the two countries who share most of Iraq's borders. Western officials have made clear they consider Syrian president Bashar Assad part of the problem and US officials opposed France's attempt to invite Iran.
France's foreign minister acknowledged that a number of the countries at the table today had "very probably" financed Islamic State's advances, and Iraq's president appeared ambivalent about Arab participation, saying his country needed the support of its neighbours but not necessarily their fighter jets or soldiers.
"Ultimately, this is a fight within Islam, within Sunni Islam," White House chief of staff Denis McDonough told Fox News yesterday.
The gathering itself was set to last just a few hours. French foreign minister Laurent Fabius said quick action was vital, insisting there was no comparison with the 2003 US invasion of Iraq, which France vocally opposed.
"It's the same geographic area but that's the only similarity," he told France Info radio on Monday. "When you are a political leader, you have to measure the cost of inaction."
Iraq's president Fouad Massoum - a Kurd, whose role in the government is largely ceremonial - expressed regret that Iran was not attending the conference.
He also seemed lukewarm to the possible participation of Egypt, the United Arab Emirates and Saudi Arabia in airstrikes in Iraqi territory.
"It is not necessary that they participate in air strikes; what is important is that they participate in the decisions of this conference," he said, underscoring Baghdad's closeness to Iran and how tensions among the regional powers could complicate the process of forming a Sunni alliance.
Speaking in his first interview since becoming Iraqi prime minister, Haider al-Abadi told state-run al-Iraqiyya he had given approvals to France to use Iraqi airspace and said all such authorisations would have to come from Baghdad.
The killing of David Haines, a British aid worker held hostage by the militants, added urgency to the calls for a coherent strategy against the brutal and well-organised group.
It is a magnet for Muslim extremists from all over the world and rakes in cash from oil smuggling, human trafficking, theft and extortion, according to US intelligence officials and private experts.
British Prime Minister David Cameron said his country would continue offering logistical help to US forces and that counter-terrorism efforts will increase, describing the Islamic State group as a "massive" security threat that cannot be ignored.