The so-called Islamic State in Iraq and the Levant terrorist group on Sunday claimed to have executed Peter Kassig, a US aid worker kidnapped in Syria, as a warning to the United States

The so-called Islamic State in Iraq and the Levant terrorist group on Sunday claimed to have executed Peter Kassig, a US aid worker kidnapped in Syria, as a warning to the United States.
  
The same video showed the gruesome simultaneous beheadings of at least 18 men described as Syrian military personnel, the latest in a series of mass executions and other atrocities carried out by ISIL.
  
"This is Peter Edward Kassig, a US citizen of your country," said a black-militant wearing a balaclava, the same outfit worn by the man who beheaded two American journalists and two British aid workers in earlier videos.
  
The man stood over a severed head bearing a resemblance to Kassig, a former American soldier who had been allegedly providing medical treatment and aid to those suffering from Syria's war.

"Here, we are burying the first American crusader in Dabiq, eagerly waiting for the remainder of your armies to arrive," the militant said.
  
Dabiq is the site of a major 16th century battle in what is now northern Syria that saw the Ottomans defeat the Mamluks and begin a major expansionist phase of an empire the ISIL group considers to have been the last caliphate.
  
In a highly choreographed sequence earlier in the video, terrorists marched at least 18 prisoners said to be Syrian officers and pilots by a wooden box of long military knives, each taking one as they passed, then forced them to kneel in a line and decapitated them.

The terrorist group has killed hundreds of Iraqi and Syrian tribesmen who opposed it, attacked religious and ethnic minorities, sold women as slaves, executed scores of Iraqi security personnel and carried out beheadings on camera.