To actually detonate a nuke it pretty much has to be armed and intentionally dropped. That said, there's a much lower barrier for scattering nuclear material al

To actually detonate a nuke it pretty much has to be armed and intentionally dropped. That said, there's a much lower barrier for scattering nuclear material all over the countryside. As an example, an implosion type bomb needs to be detonated at several places around the bomb simultaneously. It's designed such that if you don't have detonation of the explosives all at the exact same time then the pit won't make a nuclear blast. They're very safe in terms of accidental nuclear detonation, but still, if the explosives are detonated it's going to make quite a mess to say the least.