Then what is your alternative solution?

You cannot run a state, not a threateningly large state anyway, on the proceeds of kidnapping or extortion; and who are they kidnapping? Advise potential kidnap victims to stay away from ISIS and then refuse to pay ransoms for any foolish enough to ignore the advice.

Yes, ISIS has seized weapons (mostly weapons supplied to Iraq by the coalition!) but the sophisticated systems will need technical support and spare parts; denied these their performance will degrade. The whole of Syria and Iraq are awash with small-arms but these aren’t really the point; the point is to deny ISIS more sophisticated systems that would allow them to threaten the professional forces of the surrounding states.

As I’ve said, my aim would be to limit the extent and influence of ISIS, not eradicate ISIS quickly.