Israel has the bomb but that has not deterred attacks on Israel from multiple quarters. Go on, tell me why Israel didn't nuke Gaza or Lebanon, and please don't say it was because Israel is the nice guy. Pakistan has the bomb but it hasn't prevented Indian aggression or US drones from killing people on their turf. We have the bomb but it didn't deter Argentina from occupying our sovereign territory. The US has the bomb but it didn't deter 9-11. Over 200 countries do not have the bomb and the vast majority of them have not been attacked during the nuclear age. Proving that the bomb is a deterrent is like proving that God exists or that the Stones were better than the Beatles. Can't be done. The best deterrent by far is to have a non-aggressive, non-interfering foreign policy. The US and UK have a lot to learn in that regard. And the bomb is completely bloody useless against al Qaeda and Isis and they know it, and that knowledge informs their modus operandi.