The United States has decided not to use nuclear weapons against nonnuclear countries as long as they comply with their nonproliferation commitments under different international treaties. The new policy, announced today by President Barack Obama and contained in a long-awaited Nuclear Posture Review , is a departure from the United States's earlier stance of being prepared to launch a nuclear offensive against any country in retaliation to a chemical or biological attack.
In a statement  summarizing the new policy, Obama said that "the greatest threat to U.S. and global security is no longer a nuclear exchange between nations, but nuclear terrorism by violent extremists and nuclear proliferation to an increasing number of states."
Besides emphasizing the need to modernize the country's nuclear infrastructure, the review calls for boosting efforts to stop illicit trafficking of nuclear materials.
The document's release sets the stage for a nuclear security summit that will bring officials from 47 nations to Washington, D.C., next week. And next month, nations will gather in New York City to review the Nuclear Non-Proliferation Treaty.