There is a strong view that terrorists should be executed for their acts. In the main, I don’t disagree. Capital crimes desperately want capital punishment: prompt execution.
Many of these terrorists are doing their deeds in order to become martyrs and to live in Allah’s heaven. For these, execution is a reward, not a punishment; for such as these, execution is a goal devoutly to be wished, not a deterrent.
Instead, I suggest, expensive as it would be, that wherever possible, those terrorists who are acting for martyrdom should be taken alive and allowed to die of old age in a prison cell. Here is punishment for the terrorist, and here is the possibility of deterrence: the price of failure being to live a long life in a cage, to be denied death except through the senility of old age.