In nuclear-weapons policy, President Barack Obama has redefined the purpose of the U.S. nuclear arsenal. Since the birth of the atomic bomb and the onset of the cold war, these weapons have been justified as a deterrent against attack by a rival superpower. That fear no longer exists, and the Obama administration has responded to strategists’ conclusion that the real current danger has changed. Now it has become the threat of proliferation of nuclear weapons and the concurrent rising risk that nuclear weapons may fall into terrorists’ hands. As a result, the Obama administration wants to assign the U.S. nuclear arsenal and nuclear doctrine a new main purpose: increasing global political pressure against nuclear proliferation.