Stupid terrorists. They risk alienating people whenever they kill people. Dead people can't be convinced of a new ethos; friends and families of the dead (unless the dead were scumly tampons) are unlikely to re-evaluate their politics. Politicians tend to side with the dead (cf. overly stringent grave-robbing punishments). If you resort to killing, you're fucked after you start. (It was 'almost before you start', but that was nonsense and lies).
Coulda but didna's the way to go. (Reckon terrorists use their recognised codewords for claiming responsibility as their computer passwords? Good thing there's no such thing as police corruption, or they could order loads of books from Amazon and make the terrorists pay for it). Terrorists need to blow up small things, and explain that they chose not to kill, but they could have done, so vote for them or you'll get what's coming to you, buster. Bottles of milk are probably the best things. Plastic ones in supermarkets, not glass ones - don't wanna hurt anyone. Lots of people in supermarkets, lots of people who will be glad they're not dead. Even a small explosion's gonna send milk everywhere, they ain't gonna manage to clean it up from everywhere it done gone. Stinky old milk. Long-life reminder.
A thrusting young twat will try and make a name for himself in politics by challenging the terrorists and taking a supposedly hard line. "You're only blowing up small stuff as you lack the stones to blow up big stuff."
"No stones? No stones?" ask the terrorists. "He means testicles, right? That's a rather outdated and sexist attitude, Robin. 50% of our members are women and so don't have stones anyway. If you'd like us to blow up big stuff just to prove we can, then we will. We don't want to kill though. Howsabout we just put a little bit more semtex on a milk bottle in your local supermarket and just kill you? Enough proof for you?" One death.
It'll seem like a waste of explosives, but they're gonna have to get a fuckload on a plane somewhere and attach a note saying "Coulda blown this up, but didna. Remember what happened after the milk bottles. We have the stones and the ovaries (sorry, we're not very good on slang for wimlins bits). Don't come the big bassoon and think you can challenge us, cos we'll blow shit up."
Quick and easy route to the negotiating table, power-sharing, and most importantly, peace.