This graph is from Middle East Eye. It shows where the cruel ‘state’ of ISIS, present in parts of Syria, Iraq, Libya and southern Yemen gets its ideas of fanatically religious criminal ‘justice’ from: from the kingdom of Saudi Arabia, staunch allies of the Pentagon and the CIA in the USA, of David Cameron in Britain, etc. etc.
Another source of inspiration for ISIS, of course, are United States torture camps, like Guantanamo Bay. Prisoners of ISIS wear the same orange uniforms and are subject to the same torture as in Guantanamo and elsewhere.
Will Self on Political violence, a tale of 2 terrors: from Islamic State to the British State: here.