France said Thursday that it will follow the United States in launching air strikes against the Islamic State group in Iraq, as the jihadists posted their latest video of a Western hostage.
But unlike in previous grisly postings by IS in which they beheaded two American journalists and a British aid worker, British photojournalist John Cantlie was only shown speaking to camera in the style of a news report.
The French move came as Washington was set to approve plans to train and arm Syrian rebels in the fight against IS, which has gained more ground in recent days.
President Francois Hollande underlined that there would be no French air strikes against IS targets in Syria like those that his US counterpart Barack Obama authorised last week.
"I decided to respond to the request of the Iraqi authorities to offer aerial support," Hollande told reporters.
"We will not go further than that. There will be no ground troops and we will only intervene in Iraq."
The US has carried out 174 air strikes against IS in Iraq since early August, and Obama last week authorised their expansion to neighbouring Syria.
France began reconnaissance flights over Iraq on Monday from a base in the United Arab Emirates.
Britain too has conducted surveillance flights but has so far held back from launching strikes.
The US Senate was expected to back a plan, approved by the House of Representatives on Wednesday, to train and equip anti-jihadist rebels in Syria, a key part of Obama's strategy against IS.
Who exactly will benefit from the programme is unclear, as the rebels battling President Bashar al-Assad lack a clear command structure and range from secular nationalists to Al-Qaeda-backed extremists.
But Obama hailed the House approval as "an important step forward", and Senate leaders are confident it will pass Thursday for his signature.
Obama met military commanders on Wednesday and, in a speech at MacDill Air Force Base in Florida, insisted the jihadists will be defeated.
"Our reach is long. If you threaten America, you will find no safe haven. We will find you eventually," Obama said, also standing firm on his pledge that a US ground combat mission is not on the cards.
IS holds significant territory in Syria and seized large areas of Iraq in a lightning offensive in June, declaring a cross-border "caliphate" and imposing its brutal interpretation of Islamic law.
It has carried out widespread atrocities including crucifixions and reportedly selling women into slavery, and in recent weeks beheaded two US reporters and a British aid worker in chilling online videos.
The group posted a new video on YouTube showing Cantlie in an orange jumpsuit like those worn by the hostages in the previous postings, but with no immediate threat to execute him.
In the footage, Cantlie promises to reveal in a series of programmes the "truth" about the jihadist group.
Cantlie, who had contributed to British newspapers including The Sunday Times and Sunday Telegraph, as well as to Agence France-Presse, said he was captured after travelling to Syria in November 2012.
He had previously been detained along with a Dutch photographer by extremists in Syria in July 2012 but was reportedly released after nine days.
It was not clear when the video was shot, but in it Cantlie referred to recent events including the US-led campaign against IS.
In Syria, IS fighters were closing in on the country's third-largest Kurdish town of Ain al-Arab, or Kobane, on the Turkish border, cutting off its Kurdish militia defenders, a monitoring group said.
"IS fighters have seized at least 21 villages around Kobane," Syrian Observatory for Human Rights head Rami Abdel Rahman said. "The IS is using heavy weaponry, its artillery and tanks."
The town is one of three Kurdish majority districts where Kurdish nationalists have proclaimed self-rule and its capture would give the jihadists control of a large swathe of the Turkish border.
The exiled opposition National Coalition warned of "the danger of a massacre" in the area, where Kurdish militia have put up dogged resistance to the jihadists.
The US estimates that IS has 20,000 to 31,000 fighters, including many foreigners, and there are concerns that returning jihadists could carry out attacks in Western countries.
Australia said it had detained 15 people in connection with a plot to behead random civilians, in the country's largest ever counter-terrorism raids.
But analysts at the International Institute for Strategic Studies (IISS) warned against overestimating the IS threat, saying that Al-Qaeda's global network was still the bigger danger worldwide.
"Despite its spectacular acts of violence, including against Westerners, (IS's) short- and medium-term objectives appear to be local and transnational rather than global," the London-based think-tank said.
Analyst Emile Hokayem told a news conference: "We shouldn't exaggerate its potency. It is a very serious security threat to the region -- as a global threat it's still limited."