President Barack Obama told assembled leaders at the 47-country Nuclear Security Summit Tuesday the risk of nuclear attack - not by an enemy nation, but from terrorists - was on the rise despite the end of the Cold War.
In his opening address to the first full day of the summit, Obama described the new nuclear reality as a "cruel irony of history." He called the conference with the goal of locking down all nuclear materials worldwide in four years.
"The risk of a nuclear attack has gone up," Obama said, as terrorist organizations like the al-Qaida network try to get their hands on nuclear materials.
By Monday night, when Obama hosted assembled presidents and prime ministers for a dinner, the summit had already paid early dividends: China's agreement to work with the U.S. on possible sanctions against Iran and Ukraine's decision to rid itself of nuclear bomb-making materials.
Obama had already held two days of meetings with selected leaders from among the 47 countries assembled to recharge efforts to keep nuclear material out of terrorist hands. It ends Tuesday with a joint declaration to guide future work toward locking away and cleansing the globe of materials still too easily accessible to terrorists.