[Image:Nuclear weapon programs worldwide oct2006.png|thumb|300px|World map with nuclear weapons development status represented by color. ]] Nuclear proliferation is a term now used to describe the spread of nuclear weapons, fissile material, and weapons-applicable nuclear technology and information, to nations which are not recognized as "Nuclear Weapon States" by the Treaty on the Nonproliferation of Nuclear Weapons, also known as the Nuclear Nonproliferation Treaty or NPT.