ABSTRACT
Nothing could be more central to U.S. and world security than ensuring that nuclear warheads and their essential ingredients-plutonium and highly enriched uranium (HEU)-do not fall into the hands of terrorists or proliferating states. If plutonium and HEU find their way onto a nuclear black market, nothing else we do to prevent the proliferation of nuclear weapons will succeed. Similarly, unless stockpiles of nuclear warheads and fissile materials can be secured, monitored, and verifiably reduced, it will be impossible to achieve deep, transparent, and irreversible reductions in nuclear arms. Measures to control warheads and fissile materials, therefore, are central to the entire global effort to reduce nuclear arms and stem their spread.
