Army Col. Steven Warren spoke from Baghdad about the U.S. airstrike targeting "Jihadi John," saying that the Pentagon is confident that he was killed but still have to formally confirm the outcome. (AP)

The drone strike that U.S. officials believe killed “Jihadi John,” the Islamic State executioner whose beheading of Western hostages came to symbolize the militants’ brutality, appeared this week as a rare success in the struggling U.S. campaign against the group.

More than a military feat, the death of the Islamic State’s most well-known spokesman, if confirmed, would be a step forward in the U.S. effort to counter the group’s sophisticated social-media operations and to up the ante in a two-way propaganda war.

Speaking the day after the strike in Raqqa, the Islamic State’s de facto capital in Syria, U.S. military officials said they were “reasonably certain” that the two Hellfire missiles fired from an American MQ-9 Reaper drone late Thursday killed the British militant, whose real name is Mohammed Emwazi, and a second individual.

Army Col. Steven Warren, a U.S. military spokesman, did not give details about why military officials were confident that Emwazi, 27, was dead, but he said the drone strike was carried out as planned.

Warren said officials were now working to definitively establish that Emwazi was killed. His death would be a blow to the Islamic State’s public image, Warren said, even if Emwazi was not a top operational commander. “This guy was a human animal,” he said.

Foreign policy reporter Adam Goldman explains who Mohammed Emwazi is and how The Washington Post discovered his identity. (Gillian Brockell and Alice Li/The Washington Post)

In London, British Prime Minister David Cameron lauded the operation, which he described as a “combined effort” between U.S. and British forces. “If this strike was successful, and we still await confirmation of that, it will be a strike at the heart of ISIL,” he said, using an acronym for the Islamic State.

A senior U.S. defense official, who like others spoke on the condition of anonymity to discuss intelligence matters, said three drones took part in the operation, one of them British. An American plane conducted the strike.

In a statement at 10 Downing Street, Cameron described Emwazi as a “barbaric murderer” who was the Islamic State’s “lead executioner.”

“This was an act of self-defense. It was the right thing to do,” he said.

U.S. officials said the car believed to have been carrying Emwazi and another person pulled up at a two- or three-story building, a business, around 11 p.m. local time Thursday. Emwazi went inside the building for a short time, came out and got back in the car. At that moment, the American missiles destroyed the vehicle.

The Syrian activist group Raqqa Is Being Slaughtered Silently, which monitors events in the city, reported that a drone strike targeted a car near the Islamic court in downtown Raqqa shortly before midnight. It was among a dozen blasts heard during an intense wave of airstrikes, the group said on its Twitter feed.

Scores of hostages, including Westerners, have been killed by the Islamic State since 2014.

Emwazi appeared in a video in August 2014 as the unknown masked man with an English accent who beheaded American journalist James Foley.

Emwazi subsequently beheaded Steven Sotloff, another American journalist, and appeared in a video in which American aid worker Abdul-Rahman Kassig was decapitated. ­He also killed David Haines and Alan Henning, both British aid workers, and Japanese journalist Kenji Goto.

“It is a very small solace to learn that Jihadi John may have been killed by the U.S. government,” Foley’s parents, John and Diane Foley, said in a statement. “His death does not bring Jim back. If only so much effort had been given to finding and rescuing Jim and the other hostages who were subsequently murdered by ISIS, they might be alive today.”

Art and Shirley Sotloff, the parents of Steven Sotloff, said Emwazi’s death would change nothing for them. “It’s too little too late. Our son is never coming back,” they said. “More importantly, today, we remember Steven’s remarkable life, his contributions and [others who have] suffered at the hands of ISIS.”

The Obama administration attempted to rescue the Americans during the summer of 2014, when Delta Force commandos stormed a prison where they were thought to be held. Officials later concluded that the prisoners had been moved days before the raid.

U.S. officials have said that confirmation of Emwazi’s death will probably require information gleaned from intercepted militant communications. They say it is probably impossible to obtain a DNA sample, making it more difficult to establish his death conclusively.

“We could potentially never know” with certainty, another defense official said.

Emwazi is the best-known militant the United States has killed in more than a year of airstrikes against the group in Iraq and Syria.

Emwazi was born in Kuwait but grew up in London. He studied computer programming before gradually becoming radicalized. In 2010, British authorities detained Emwazi and barred him from leaving the country. He is believed to have traveled to Syria around 2012 and later joined the Islamic State.

Emwazi was one of a group of English-speaking militants that former hostages dubbed “the Beatles.” Those former prisoners described Emwazi as a frequently brutal captor who took part in waterboardings and beatings. It’s not clear if one of the so-called Beatles was the other passenger in the destroyed car.

While the stature of Emwazi and his fellow English-speaking militants was enhanced by the propaganda effect of the execution videos, which drew intense international attention, his operational influence was limited.

Peter Neumann, director of King’s College’s International Center for the Study of Radicalization, said Emwazi was a “low-ranking officer.” Symbolically, Neumann said, his death would show that the Islamic State is reeling, which could undercut recruitment.

“It feeds into the narrative of ISIS, in its core territory, losing,” he said.

While the Obama administration has said it has contained the expansion of the Islamic State in Iraq and Syria, local forces have been unable to dislodge militants from important cities. At the same time, Islamic State affiliates have spread across the region.

Faysal Itani, a Middle East expert at the Atlantic Council, a Washington think tank, cautioned that the Islamic State still counts on substantial support in the region.

“Killing a high-profile propagandist is in itself a significant propaganda win,” Itani said. “But this organization is extremely adaptable and, so long as it has access to an aggrieved Sunni population, will always reemerge in one way or another.”

Witte reported from London. Julie Tate and Thomas Gibbons-Neff in Washington, Karla Adam in London, and Liz Sly in Beirut contributed to this report.

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