Nuclear weapons are the word's most powerful weapons. They acquire power from nuclear reaction, either nuclear fission as did the original World War II designs, or by nuclear fusion as do more powerful thermonuclear weapons. The inherent dangers that accompany existence of such powerful devices were recognized early and resulted in several attempts to ban them. However, this vision has not yet materialized and while several regimes regulate the states behavior in the realm of nuclear weapons world’s great powers still consider their possession rather necessary for foreseeable future.