At the turn of the millennium, five countries were acknowledged nuclear weapons states. Two had demonstrated a nuclear-weapon capability and it is thought that only one, Israel, with a capacity for about 200 warheads, remained undeclared. North Korea may have produced a small number of nuclear weapons. At the peak of production in the eighties, there were about 70,000 nuclear weapons in the world — with an explosive power equivalent to 500,000 bombs of the size dropped on Hiroshima and Nagasaki. India was thought to hold more than eighty nuclear weapons to Pakistan’s twenty-five. China had 400; Russia 21,000; the United States 11,500; France 450; and the United Kingdom 260. Just one 15-kiloton fission bomb explosion over an urban area with a population density of about 25,000 per square kilometre would kill about 200,000 people.