Should nuclear weapons be abolished? To many, the answer might seem obvious given the economic cost and, more important, the destructive power of these weapons. The use of just a small percentage of the tens of thousands of weapons that exist could kill millions of people and leave large areas of the Earth uninhabitable for generations. For better or worse, however, the question of abolishing nuclear weapons is actually quite complicated. Nevertheless, the best answer to the question of whether they should be abolished in the foreseeable future turns out to be “no.” Still, it would be unwise to assume that such weapons will forever remain unused simply because individuals and governments have exercised restraint to date. If deterrence should break down for any reason, the human toll of any nuclear weapons use would be great. The bombs dropped by the United States on the Japanese cities of Hiroshima and Nagasaki in the final days of World War II (1939-1945) demonstrated the awful destructive power of what were two relatively small and primitive weapons. Today’s bombs are far more powerful and, if they were used, would therefore cause damage on a far greater scale. This is what deterrence, or prevention, is all about. Deterring a nuclear war requires making sure that your adversaries know that they will not benefit from using nuclear weapons first. This, in turn, requires that all parties maintain “second strike” capabilities—that is, the ability to survive a nuclear attack and still retaliate so that the side striking first gains no advantage. Safety will be the sturdy child of terror, and survival the twin brother of annihilation, vividly captures this concept. Indeed, this idea of mutual vulnerability, or mutual assured destruction, is so central to deterrence that it was codified by the then-superpowers in a 1972 treaty that severely limited defense against ballistic missiles. Would a world without nuclear weapons be more peaceful? Not necessarily. War was commonplace between and within states for the centuries of recorded history before the advent of the nuclear age. There is little reason to believe that human nature has progressed to the point where the traditional sources of conflict—ideologies, nationalism, religion, greed, ambition—are even close to being obsolete. A nuclear weapons-free world would be better off in the sense that a cataclysmic conflict was no longer a possibility, but arguably worse off in the sense that lesser but still terrible forms of conflict would become less risky and hence more frequent. Managing the transition to a world without nuclear weapons would be difficult, as even a small amount of cheating could have significance. What would have to change for it to be both possible and safe to move to a nuclear weapons-free world? Nothing less than a basic transformation of international politics would be required. Tensions between governments would have to fade dramatically; trust between them would have to grow. Abolition of nuclear weapons in and of itself would not bring about an abolition of tension or conflict. To the contrary, it would lead to a world of more frequent violence if the restraining features of nuclear deterrence were removed and not replaced by better political relations. Such consensus and sense of community is a long way off. For now, nuclear weapons are a condition to be managed rather than a problem to be solved.