John Bacon

USA TODAY

The parents of Peter Kassig, an American humanitarian aid worker being held by Islamic State militants, released a video Saturday pleading for the former Army Ranger's release.

Kassig, who his parents say has changed his first name to Abdul-Rahman, is shown kneeling next to a militant in a video released Friday that first shows the beheading of a British aid worker. "Obama, you have started your aerial bombard of Shams (Syria), which keep on striking our people, so it is only right that we strike the next of your people," the masked militant says with Kassig at his side.

His parents, Ed and Paula Kassig of Indianapolis, ask in their video that his captors "show mercy and use their power to let our son go."

Peter Kassig, 26, was seized a year ago near Raqqa, Syria. Ed Kassig, a schoolteacher, says his son has embraced Islam and loves the Syrian people.

"We know that Syrians are suffering," Ed Kassig says. "We also believe that violence is not the solution to the problems that trouble us all. There is so much beyond our control. We asked our government to change its actions but, like our son, we have no more control over the U.S. government than you have over the break of dawn."

Paula Kassig then speaks directly to their son, saying she is proud of his efforts on behalf of the Syrian people.

"Know that we love you, and our hearts ache for you to be granted your freedom so we can hug you again and then set you free to continue the life you have chosen, the life of service to those in greatest need," Paula Kassig says.

The video released Friday by Islamic State — also known as ISIL — militants shows the beheading of Alan Henning, 44, a Manchester cab driver. Henning was working with a humanitarian mission when he was taken prisoner in Syria last December.

"I am Alan Henning. Because of our Parliament's decision to attack the Islamic State, I, as a member of the British public, will now pay the price for that decision," Henning says in the video.

In recent weeks, the militants have released videos showing the beheading of American reporters James Foley and Steven Sotloff and British aid worker David Haines. In the Haines video, the militants warned that Henning would be next.

Henning's wife, Barbara, released a video last week asking ISIL to "spare Alan's life." After his death, she issued a statement saying the family was "numb with grief."

In Britain, Prime Minister David Cameron said Saturday that the latest beheading would only strengthen global resolve to hunt down the killers and crush the advance of ISIL militants in Syria and Iraq.

"ISIL's brutality will not persuade us to change our approach," Cameron said. "Indeed, the senseless murder of an innocent man only reinforces our resolve to defeat this terrorist organization and to eradicate the threat they pose."

"We will use all the assets we have to try and help those hostages … and defeat this organization, which is utterly ruthless and barbaric," Cameron said.

On Friday, President Obama released a statement condemning the beheadings.

"Mr. Henning worked to help improve the lives of the Syrian people and his death is a great loss for them, for his family and the people of the United Kingdom," the statement said. "Standing together with our UK friends and allies, we will work to bring the perpetrators of Alan's murder — as well as the murders of Jim Foley, Steven Sotloff and David Haines — to justice. Standing together with a broad coalition of allies and partners, we will continue taking decisive action to degrade and ultimately destroy ISIL."