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A video released by Islamic State shows fighters carrying out a mass execution by beheading Syrian rebels.
ISIS threaten bloodshed against any Muslims thinking about joining US-backed groups looking to over-throw the Assad regime in the war-torn Middle East.
Two fighters talking in the video proclaim the group will not stand for anything other than an Islamic State-run Syria, before members of the Free Syrian Army - who are filmed performing Nazi salutes, say ISIS - are brutally murdered.