She will be!
Killing them makes them martyrs. Putting them in prison shows us to be weak (by their standards we'd be beheaded) and they use that for political mileage too. I say zero tolerance is the only position to take.
Did terrorism work for the IRA? Did it work for the PLO? Sure they got noticed but, eventually, they both turned to diplomacy and probably accomplished more in the end. The way I see it these extremists are all psychopaths and, as such, are just looking for justification for their need to kill.