As the US leader urge the UN General Assembly to join the fight, Belgium and the Netherlands committed warplanes to Iraq and Britain said its parliament would vote Friday on following suit.
“The United States of America will work with a broad coalition to dismantle this network of death,” Obama told the UN about the Islamic State group. “I ask the world to join in this effort.”
An IS-linked group in Algeria, which had demanded France halt its participation in the strikes, on Wednesday posted video footage of the execution of an abducted Frenchman.
“We will use our military might in a campaign of air strikes to roll back ISIL,” Obama declared, using the acronym for the former Islamic State of Iraq and the Levant, since renamed the Islamic State.
Overnight, US-led air raids targeted IS fighters threatening the Kurdish regional capital in Iraq and damaged eight militant vehicles operating in eastern Syria near the Iraqi border.
The US-led campaign, Saudi Arabia, Bahrain, the United Arab Emirates and Jordan have hit targets in Syria and France in Iraq, took center stage at the United Nations.
Obama and French President Francois Hollande led international condemnation of murder of the French hiker, 55-year-old Herve Goudel by Jund al-Khilifa, a group linked to IS.
Paris opposed the 2003 US-led invasion of Iraq but has sent Rafale fighters into action over Iraq — but not to the parallel campaign in Syria — and Hollande vowed not to give in to the IS group.
“The fight against terrorism must continue and be stepped up,” Hollande said.
IS militants in Syria had already killed two American journalists and a British aid worker, but Goudel’s death was the first at the hands of an allied group outside the core area since the US campaign began.
Obama said the United States stood with France and chaired a UN Security Council meeting which unanimously adopted a binding resolution to stem the flow of foreign fighters to Iraq and Syria.
It requires all countries to adopt laws that would make it a serious crime for their nationals to join jihadist groups such as Islamic State and Al-Nusra Front, or risk economic sanctions or military action.
Jordan’s King Abdullah II, whose country is sheltering nearly 1.4 million Syrians, told the UN General Assembly there had to be a collective strategy to defeat militants who threaten global security.
In their capitals, Belgium and the Netherlands said they would each send six F-16 fighter bombers to join the air campaign in Iraq.
Apart from the F-16s, the Netherlands will also deploy 250 military personnel and 130 trainers for the Iraqi military.
The Belgian parliament must still approve the move, which follows a formal request from Washington on Tuesday, Defense Minister Pieter De Crem said.
On the sidelines of the assembly, Prime Minister David Cameron said the British parliament would hold an extraordinary session on Friday to vote joining the strikes, as requested by Baghdad.
On Tuesday, the Pentagon said air raids and cruise missiles had killed the Khorasan group of Al-Qaeda veterans, allegedly plotting an “imminent” attack against US and Western interests.
US aircraft have carried out 198 air strikes against the jihadist group in Iraq since August 8 and 20 in Syria since Monday.
Al-Qaeda’s Syrian branch, the Al-Nusra Front, said Wednesday that it was evacuating its bases and positions in the northeastern Syrian province of Idlib.
Ahrar al-Sham, a key Islamist rebel group allied with Nusra, was also evacuating its positions in the region, the Syrian Observatory for Human Rights monitoring group said.
Obama later hailed the “political vision” and inclusive nature of new Iraqi Prime Minister Haidar al-Abadi as the two leaders met for the first time.
He used his talks with Abadi to portray the new prime minister as the right kind of leader for Iraq as it struggles to expel radicals from the Islamic State group from its territory with the help of US strikes.
More than 40 countries have aligned themselves with the US-led campaign but a question mark hangs over Iran, which backs the Iraqi government but is also an ally of Syrian President Bashar al-Assad.
Separately, Britain’s premier held talks at the United Nations with Iran’s President Hassan Rouhani, the first meeting between the countries’ leaders since the 1979 Islamic Revolution.
Rouhani posted a photograph of himself smiling as he shook hands with Cameron at the British mission at the United Nations.