Nuclear warheads have multiple safeguards against detonating without intention. While there are actually quite a few not specifically mentioned this article is

Nuclear warheads have multiple safeguards against detonating without intention. While there are actually quite a few not specifically mentioned this article is a good start. https://en.wikipedia.org/wiki/Permissive_Action_Link https://en.wikipedia.org/wiki/Permissive_Action_Link Even in the event of fire, explosion, etc warheads are unlikely to detonate unintended. Missle failures are quite common and a few have happened during atmospheric nuke tests and no detonation occured and many of these test weapons had few of the safeguards on duty weapons have.