PARIS -- The cold-eyed militants lined up behind their victims in the latest Islamic State video appear to come from outside the Middle East, including one from France and possibly two from Britain, as the extremist group tries to show a global reach.

The grisly video -- clearly aimed at a Western audience -- lingers as much on the faces of the camouflaged extremists as the men who are beheaded. The victims include American aid worker Peter Kassig and more than a dozen Syrian soldiers.

The images of the Islamic State militants, who are shown one by one in close-up, allowed authorities to identify one of them Monday as a 22-year-old Frenchman who converted to radical Islam.

Maxime Hauchard has been on the radar of French authorities since 2011 when he took two trips to Mauritania to attend a Quranic school, said Paris prosecutor Francois Molins. The prosecutor said investigators were trying to determine if another Frenchman also is in the video.

President Barack Obama confirmed Kassig's slaying after a U.S. review of the video.

The overwhelming majority of Islamic State fighters are from the Mideast, but the extremist group is trying to cement its claim on an Islamic empire straddling Iraq and Syria. Europe appears to be a fertile ground to find supporters, with officials saying thousands of young Europeans have headed off to jihad. More than 1,000 people in France alone are under surveillance for suspected plans to join the militants, officials said.

In the video released Sunday, some of the knife-wielding extremists standing behind their kneeling victims had distinctly Asian features. Another whose face was hooded had the familiar London accent of the jihadi who also appeared in beheading videos with American hostages James Foley and Steven Sotloff, and with British hostages David Haines and Alan Henning. There also were indications that a Welsh medical student may be the man standing next to Hauchard.

"It's quite transparent that IS is trying to exaggerate its base of support," said Charlie Winter, a researcher at the Quilliam Foundation in London. "They are trying to show that Muslims from all over the world are protecting their Syrian brethren and their Iraqi brethren."

European officials are trying just as furiously to counter that message.

"I call solemnly and seriously on all our citizens, and notably our young people who are the primary target of the terrorist propaganda, to open your eyes to the terrible reality of the actions of Daesh," said French Interior Minister Bernard Cazeneuve, using an Arabic acronym for the Islamic State group. "These are criminals that are building a system of barbarity."

Hauchard gave an interview to France's BFM television in July, telling the network he had helped capture Mosul, the Iraqi city whose fall eventually prompted the United States to resume military operations in Iraq.

"We're waiting for death," Hauchard said at the time. "My objective is to be a martyr."

A man from Wales, Ahmed Muthana, said he thinks he saw his son, 20-year-old Nasser Muthana, in the latest video, and Winter, the British researcher, confirmed the likeness.

"It resembles him. I was shown a picture of the video. I cannot confirm it is him, but I think it might be," Ahmed Muthana told Britain's Press Association.

Kassig had gone to Syria on a humanitarian mission. His parents, Ed and Paula Kassig, said Monday that while their hearts have been shattered by his death, they believe his life is proof that "one person can make a difference."

"In 26 years, he has witnessed and experienced firsthand more of the harsh realities of life than most of us can imagine," Paula Kassig said in Indianapolis, Indiana, reading a brief statement. "But rather than letting the darkness overwhelm him, he has chosen to believe in the good -- in himself and in others.

As for the French militant in the video, Molins said he had used aid work as a pretext.

"The humanitarian action was a facade. In fact, he wanted to fight and join Islamic State agents," Molins said.

With Kassig's death, the Islamic State group has killed five Westerners it was holding.

Unlike previous videos of slain Western hostages, the latest one did not show the decapitation of Kassig, the moments leading up to his death or threaten to kill any other Western hostages.

It identified the militants' location as Dabiq, a town in northern Syria that the Islamic State group uses as the title of its English-language propaganda magazine and where they believe an apocalyptic battle between Muslims and their enemies will occur.

The high-definition video also showed the beheadings of about a dozen men identified as Syrian military officers and pilots, all dressed in blue jumpsuits.

All of the militants wore brand new camouflage uniforms, except for the black-clad man who spoke with a British accent and warned that U.S. soldiers will meet a similar fate.

"We say to you, Obama: You claim to have withdrawn from Iraq four years ago," the militant said. "Here you are: You have not withdrawn. Rather, you hid some of your forces behind your proxies."

A U.S.-led coalition is targeting the Islamic State group in airstrikes in northern Syria, supporting Western-backed Syrian rebels, Kurdish fighters and the Iraqi military. The U.S. said 31 airstrikes had been carried out from Nov. 14-17 against Islamic State group targets.

U.S. Secretary of State John Kerry said the Islamic State group could grow worldwide if left unchecked. Already, he said, the IS has seized more land and resources "than al-Qaida ever had on its best day of its existence."

IS "leaders assume that the world will be too intimidated to oppose them," Kerry said. "But let us be clear: We are not intimidated."

Kassig served in the U.S. Army's 75th Ranger Regiment, a special operations unit, and was deployed to Iraq in 2007. After being medically discharged, he returned to the Middle East in 2012 and formed a relief group, Special Emergency Response and Assistance, to help Syrian refugees.

The Islamic State group still holds other captives, including British photojournalist John Cantlie, who has appeared in several videos delivering statements, likely under duress, and a 26-year-old American woman captured last year in Syria while working for aid groups. U.S. officials have asked that the woman not be identified for er safety.

The group's militants have beheaded or shot dead hundreds of captives, mostly Syrian and Iraqi soldiers, celebrating the mass killings in graphic videos.

The Islamic State group has declared a self-styled Islamic caliphate in areas under its control, which it governs according to its violent interpretation of Shariah law.

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Associated Press writers Gregory Katz in London, Elaine Ganley in Paris, Diaa Hadid in Beirut, Dylan Lovan in Indianapolis and Matthew Lee in Vienna contributed to this report.