ISIS has threatened the life of Peter Edward Kassig after releasing another video of the brutal murder of UK aid worker Alan Henning on Friday.

Kassig can be seen at the end of the video as the next Westerner in line to be executed by the masked gunman, dubbed 'Jihadi John'.

Kassig, who is only 26 years old, is a native of Indianapolis and attended Butler University. He was previously deployed to Iraq in 2007 as an Army Ranger.

He was working as a humanitarian aid worker in the area and was running an NGO called SERA, which stands for Special Emergency Response and Assistance. Prior to his capture, he had helped deliver food and aid to refugee camps in Syria.

After the video of Henning's beheading emerged, which showed the appearance of Kassig, his family released a statement: "The Kassig family extends our concern for the family of Alan Henning. We have read about his work and his generous character with great respect and admiration. We ask everyone around the world to pray for the Henning family, for our son, and for the release of all innocent people being held hostage in the Middle East and around the globe."

The video purporting to show the video of Alan Henning is a familiar sight, with the victim dressed in a bright orange jumpsuit. A masked gunman is waving a knife around.

Prior to the beheading, Henning speaks to the camera about the British Parliament's decision to join America in the bombing campaign against ISIS.

After the brutal murder, the camera shifts to American Peter Kassig, who ISIS threatens to kill next.

Henning was part of a group of volunteers that traveled to Syria in December 2013 to help bring food and water to those affected by the civil warn. He was captured by masked gunman just after Christmas.

After the video went live, Prime Minister David Cameron vowed to bring jthe killers to justice and stated: "The brutal murder of Alan Henning by ISIL shows just how barbaric and repulsive these terrorists are. Alan had gone to Syria to help get aid to people of all faiths in their hour of need. The fact that he was taken hostage when trying to help others and now murdered demonstrates that there are no limits to the depravity of these ISIL terrorists."

The White House also released a statement after Henning's death: "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.

"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."