Terrorists are like zombies - they have no capacity for human empathy, they cannot be reasoned with, the only way to eliminate their kind is to exterminate them.
A similar thought process must surely have gone through the heads of these folks as they killed 172 children. You can't work with these progressives, you can't convert 'em - the only way to wipe their scourge from the earth is to exterminate them.
Helps to start with the kids, as without kids a population will inevitably die off.
Which is the basic frame we're looking at here. ISIS as an example, but not an exclusionary one, wants a clearly defined zone of influence within which they have absolute control. Anyone who doesn't fit their prescription is a threat to be eliminated.
Once a home base has been established, you can look towards expansion.
But saying one who terrorizes is a terrorist is like saying a corporate CEO who happens to have kids a mom - it's framing them as one thing, one simply-communicated frame of reference that doesn't provide a complete picture.
Are terrorists zombies? Depends on your point of view, but I'd argue no - no more than partisans are, or followers of a religion, or any minority group.
They are human. As such, they are complex creature that are part of a complex system. They can only be understood as such.
We get that conditions like asthma or cancer can have environmental causes; we're even recognizing that mental illnesses like depression and anxiety can have environmental causes. At the same time, we recognize that those environments can be changed, that internal tools can be developed to remedy or avoid such illnesses.
Diabetes Type II is a massive social burden. It's entirely avoidable. The costs related to smoking are equally avoidable, but in both cases it's not enough to tell people "don't eat too much fat" or "stop smoking" because there are other factors involved.
Through the rise of fields like behavioural economics and a deeper understanding of neurochemistry, policy makers and sales folk are finding better ways to work our internal hardwiring to produce the results they want, though invariably there's an element of design-thinking involved (designing products/services that actually work for us on a nearly intuitive level).
This is a bit like sociology, however, and involves a willingness to work with The Other. That takes time. If you feel that time is short or some threat is great, you need to get things done quickly, which leads to a my-way-or-the-highway proposition.
You're with us, or against us. Pick your side and face the consequences, but we're moving ahead regardless.
You can't negotiate with terrorists - we don't want to negotiate with terrorists.
Human beings, however, we can work with. Heck, we can even find common ground with them.
But to accept others as human beings on par with yourself is to admit the atrocities they commit are ones you yourself are capable of. And, perhaps, are already perpetrating against those you've conveniently identified as inhuman.
There's nothing new in this basic lesson but by God, it looks like we're going to have to learn it again.