The Islamic State has released a video purportedly showing the beheading of British hostage Alan Henning.

Henning’s execution follows the beheadings of US journalists James Foley and Steven Sotloff and British aid worker David Haines in the last six weeks.

Henning, a taxi driver who went to the region to help with aid efforts, was shown in the Sotloff video as the next hostage to die if US-led airstrikes against the Islamic State continued in Iraq.

Since then, the US has launched its aerial intervention against the jihadists in Syria.

Henning was abducted in December, soon after he entered northwest Syria with an aid convoy. Syrian activists and British Muslim groups and clerics had joined Henning’s family in appealing for his release.

In today’s video, American Peter Kassig is shown as the next hostage who will be killed if Washington does not halt its operations.

Kassig, a veteran of the Iraq War, was helping the wounded in a hospital in Lebanon when he was profiled in June 2012 by CNN. He then started Special Emergency Response and Assistance to help with food, medical supplies, and clothing for Syrian refugees.

In October 2013, Kassig was working in Deir Ez Zor in eastern Syria when The Daily Beast wrote about him. The city was taken over this summer by the Islamic State.