A short video released by ISIS on Friday shows the apparent beheading of British aid worker Alan Henning, with the executioner blaming the death on the United Kingdom for joining the U.S.-led bombing campaign against the group.
Henning is the fourth Westerner beheaded in an ISIS video. Like the others, the video shows and English-speaking, masked militant waving a knife over the kneeling hostage. Henning joined an aid convoy last December and was taken hostage soon after crossing from Turkey into Syria.
Prime Minister David Cameron calling Henning's executioners "barbaric and repulsive." President Obama said the U.S. and its allies will bring the perpetrators to justice.
The video is similar to the previous ones, with a clearly scripted statement being delivered by the victim. But unlike the previous ones, this one is shorter and is shot tightly, showing none of the surroundings.
And just like the previous videos, it ends with a threat to another hostage.
The National Security Council confirmed that Kassig is being held by ISIS.
"We will continue to use every tool at our disposal - military, diplomatic, law enforcement and intelligence - to try to bring Peter home to his family," according to agency spokeswoman Caitlin Hayden.
The American who appears at the end of the video, Kassig, is a former soldier who became an aid worker in the Middle East.
Kassig's parents, Ed and Paula, confirmed to CNN it was their son, "who was doing humanitarian work in Syria, is being held captive."
CNN's Arwa Damon profiled Kassig when he was helping wounded Syrians in Lebanon in June 2012. She's OutFront.
In a video released by ISIS Friday, British aid work Alan Henning appears to have been beheaded at the hands of the terrorists. In the same video, American aid Peter Kassig appears nearby, kneeling, with an ISIS militant standing by his side.
If ISIS continues with its now familiar, brutal pattern, that American is likely to be the next victim. Republican Congressman Chris Smith, a senior member of the House Foreign Affairs Committee, joins Jim Sciutto.
Mortars were heard in Baghdad's green zone Wednesday, as U.S. forces continued to pound ISIS targets in both Iraq and Syria. The crucial nation of Turkey, which shares a border with both Iraq and Syria, has finally agreed to join the fight.
The man tapped by the Obama administration to coordinate the international effort against ISIS tells CNN's Elise Labott exclusively that the war won't be swift.
General John Allen says training Syrian rebels, who are key to fighting the terror group on the ground, is going to take a long time.
"Over the long-term, the intent is to build credible forces, vetted forces," Allen told Labott. "We have been saying that all along, it is going to take a while. It could take years actually... and so we have to manage our expectations."
As for Iraq, it doesn't look like the fight against ISIS there will end anytime soon either.
CNN's Tom Foreman is OutFront.
(CNN) - Rep. Paul Ryan doubts President Barack Obama will be able to maintain his promise that there will be no American boots on the ground in the fight against ISIS.
"I'm supportive of what the President has done going into Syria and Iraq, but you have to see this thing through," the Wisconsin Republican said Tuesday on CNN's "Erin Burnett OutFront."
Obama suggested in an interview with CBS' "60 Minutes" that his policy of sending no U.S. combat troops will stay in place. The situation in the region is more a political problem than a military one, he said.
According to a CNN/ORC International poll, the overwhelming majority of Americans (73%) support the current airstrike campaign but less than four in 10 favor sending combat troops into Iraq and Syria.
If Obama's administration ultimately comes to Congress with a plan to send combat troops to Iraq and Syria, Ryan said he would support it.
"I think the President should come to Congress with an authorization of force resolution and I would support it," he said. "And I would help the President pass that because I think it's necessary to see this threat through."
"We need to destroy ISIS, and we need to do what it takes to destroy ISIS," he continued.
FBI director James Comey says he is "not confident at all" that airstrikes in Syria disrupted an imminent plot to attack America. The administration said stopping that plot was the reason for its first major strikes on Syria.
Comey went on to say an attack in the U.S. could happen at any time, as soon as "tomorrow."
OutFront, Pentagon Spokesman Rear Admiral John Kirby.