A nuclear weapon is used to prevent being threatened by other nuclear countries. Say, for example, France got rid of all of it's nuclear weapons, tiny countries that had a nuclear weapon would be able to bully them into accepting bad deals or presurring them into not reacting when things happen. Most countries in the world would probably like to dispose of their nuclear weapons but they can not due to the fact of little countries with problems that will keep them would be able to threaten them and hold the world by it's throat.
When Someone Wants A Nuclear War , You Are Defended
The man has fists to hit,the legs to kick ,stone,knife,gun,M-16,missel and,of course,the nuclear weapons,all of these are defense for safety of life ,after the safety that will be happiness;but at each century,the war is existed;Nuclear weapon is a kind of weapon.
The meaning of the word nuclear weapon, is a weapon that has a nuclear warhead on it.
The provision of component and safety redundancy and diversity in nuclear reactors is important to enhance safety of nuclear reactor operation.
You can deviate away from the rules when someone else does it first.
A nuclear weapon must be armed before it can be used. They are all built with safety mechanisms so they will not go off accidently or on impact after the crash of a delivery vehicle.
USA, Russia, UK, PRC, France, India, Pakistan, North Korea are known for having nuclear weapon. Israel probably also owns nuclear weapon but never officialy declared it.
This nuclear weapon is called an atomic bomb or a nuclear bomb
An atomic weapon is an alternative name for a nuclear weapon, a weapon which derives its energy from the nuclear reactions of either fusion or fission.
Nuclear weapon detonations
If by "bomb" you mean a conventional explosive weapon, then the nuclear weapon is more powerful.
To defend against someone else having them. Same as any other weapon.