Peter Kassig beheading - Islamic State militants claim to have beheaded a fifth western national in a chilling video released on Sunday.

In the 16-minute video posted on the terrorists' social media platforms, a masked man is shown standing over what he claims to be the decollated head of the former soldier and aid worker.

The Islamic State executioner, identified as 'Jihadi John' by the media, says "This is Peter Edward Kassig, a U.S. citizen of your country, who fought against the Muslims in Iraq while serving as a soldier in the American army."

Unlike other Islamic State propaganda videos, this clip did not show the exact moment of Peter Kassig's beheading. The latest ISIS release however showed the gruesome beheadings of about 16 men who are purported to be Air Force personnel from the Syrian Army.

Before a row of Islamic State militants behead the alleged Syrian soldiers, Jihadi John warns President Obama and the U.S. saying, "To Obama, the dog of Rome. Today we are slaughtering the soldiers of Bashar and tomorrow we will be slaughtering your soldiers. And with Allah's permission we will break this final and last crusade. And the Islamic State will soon, like your puppet David Cameron said, begin to slaughter your people in your streets."

Peter Kassig's beheading comes as the U.S. and her allies are increasing their attacks on the ravaging terrorists. The 26-year-old served in Iraq in 2007, but was honorably discharged after a short stint for medical reasons. He founded an aid organization, Special Emergency Response and Assistance (SERA), which provides aid to Syrian refugees. He was kidnapped by Islamic State militants in October 2013 while on humanitarian work in Syria.

Reports indicate that prior to Peter Kassig's beheading; he had been forced to convert to Islam and changed his name to Adbul-Rahman.

The White House has revealed that the authenticity of the video is still being determined. Nonetheless, spokeswoman for the National Security Council, Bernadette Meehan, has extended condolences to the Kassig family. She described the murder as appalling.

British Prime Minister David Cameron, who was mentioned in the Peter Kassig beheading video, has also condemned the act.

"These beheadings show once again what a depraved organization this is," he said. "Like others who have been murdered in cold blood by ISIL, Abdul-Rahman Kassig was a selfless humanitarian worker who had gone to the region to help care for those fleeing the Syrian conflict."

Since the Peter Kassig beheading video was released, his parents have released a statement urging the media not to propagate the Islamic State propaganda by publishing extracts from their latest video.

"We prefer our son is written about and remembered for his important work and the love he shared with friends and family, not in the manner the hostage takers would use to manipulate Americans and further their cause," their statement said.

Peter Kassig's beheading does not really come as a surprise. Last month, the Islamic State announced that Peter Kassig's beheading was impending after they murdered British aid worker Alan Henning.