The footage, which was aired on Sunday, shows the masked terrorist claiming to have chopped off Kassig’s head as a warning to the government of the United States. However, there has been no verification of the clip.
The 26-year-old American was kidnapped in October 2013 on his way to Syria’s eastern city of Deir al-Zour.
The nearly 16-minute video also shows what appeared to be the mass execution of several abducted Syrian soldiers.
The ISIL militants first showed Kassig in the video of the beheading of British aid worker Alan Henning in early October. The terror group has posted numerous videos of its atrocities as a terror tactic.
ISIL have executed several foreign nationals including American journalists James Foley and Steven Sotloff and British aid workers David Haines, and Henning.
The ISIL terrorists currently control large areas of Iraq. The group sent its militants into Iraq in June, seizing large parts of land straddling the border between Syria and Iraq.