ISIL bomb-making: professional and industrial

People with skills will eventually find their way back to Western countries, if they are not already there.

"Islamic State went through its own industrial revolution. It got a workforce to produce a seemingly endless, high-quality stream of death machines and IEDs. No longer do the jihadis seem dependent on a small, secretive and highly skilled circle of bombmakers sought out by US drones and western intelligence officials."

"Instead of standard detonator cord, for example, Isis uses an electrical cable that, when cut, detonates, not deactivates, a device, they say. Other devices are not activated by pressure but when pulled from the ground, something clearance teams would typically do."

https://www.ft.com/content/58d37762-9ce3-11e6-a6e4-8b8e77dd083a