The only proper solution is to gather enough intel to know exactly where each major group or subdivision of the Islamic state is, go after a group, and repeat.
The better solution is to do this, but to also have all local governments that appear to be housing this group to co-operate so this is all done within the same 24-48 hours.
I think this is a good solution without having to create another quagmire in Syria or what not, because ISIS is also a group that is small. This was a tally from last year:
http://www.cbc.ca/news/world/isis-b...ch-the-militant-organization-may-be-1.2746332
Any army of 20k (let's say) in 2015. But has no nation. They are split up on top of that, and even if they are armed to the teeth, taking them out in a co-ordinated fashion should be possible.
It means also that you'd have to co-operate with one "evil" government to eliminate another. Because we all know what happens if you try to force your own government onto others...
No tolerance. Instant death penalty - immediately shoot them in the head? Obviously that's very extreme. I don't know either.
Yeah I don't know how they trigger the devices - is it by hand or something? Either way, the moment you realize they have it on them (and it's mostly likely a law enforcement guy), they'll probably pull it within 2-3 seconds. You would have to be an expert shot to pull it off...
Dogs or a type of animal with a sensitive smell might be the best answer. I'm sure strapped explosives have a particular smell that you can't get away from.