How much do you know about nuclear weapons? Take our quiz.
The nuclear arms race that began during World War II, then escalated throughout the cold war, has left more than 17,000 nuclear warheads scattered around the world, according to the Federation of American Scientists.
Nine countries have such weapons, and multiple treaties have sought to curb their proliferation and regulate their storage. But, while some countries have dismantled or disposed of their weapons, others are thought to be building them, or at least trying to acquire the ability to do so.
How much do you know about the science, history, and politics behind nuclear weapons?
1. To begin with, why are the weapons called "nuclear"?
Nuclear energy plants provide the huge energy input needed for their manufacture.
The process of nuclear fission, which drives them, was first observed inside the nucleus of a living yeast cell.
Their explosive energy is released when the nucleus of an atom is split apart.