$1:
What the Nazi era can teach us about deradicalizing extremists
1. First, bomb them into the stone age.
2. Then require their unconditional surrender and kill every last one of the bastards who won't agree to that.
3. Execute their leaders to make sure the movement doesn't arise again.
4. Ban their propaganda materials and imprison anyone who tries to proselytize from them.
5. But first find the balls and the resolve to do all of the above.

Point 1. would require no ordnance as they are already there.