The one essential ingredient for making a nuclear weapon is fissile material, otherwise known as special nuclear material, or SNM.
By far the most common types of SNM are uranium 235 (U235) and plutonium 239 (Pu239). According to the unclassified literature, 4 kg of Pu239 or 25 kg of U235 is considered sufficient to build a nuclear weapon. There are already many tons of both these materials on the planet today. Any state or terrorist organization that manages to get its hands on the amounts of SNM mentioned above will have the bomb, PERIOD. Forget five to eight years. The reality is a great deal grimmer. It is not necessary to have a degree in nuclear engineering to understand why.
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