by former Senator Sam Nunn, Co-Chairman of the Nuclear Threat Initiative
The gravest danger in the world today is the threat of a nuclear attack. Whether launched by a state or a terrorist group, a nuclear explosion in a major city could kill hundreds of thousands, close borders, erode civil liberties, slash trade and travel, and change the world as we know it. No country would escape the consequences. Preventing the spread and use of nuclear weapons should be the top security priority of the 21st century. But this is not something that can be done by any one nation; it has to be done by many nations, working together.