But after lofty rhetoric and a few steps forward, Obama is facing fresh doubts about whether he is willing to take the political, diplomatic and budgetary risks that may be needed to bring his vision closer to reality.
At home, arms-control advocates who once extolled his ambitious plans are complaining about funding cuts for several key nuclear security programs, while critics on the right are leveling election-year accusations that his policies weaken America's strategic deterrence.
At the same time, Obama's efforts to spur global cooperation to prevent nuclear terrorism, which he once called the "single biggest threat" to U.S. security, have been overshadowed by the more urgent challenges of thwarting Iran's and North Korea's nuclear development.
All of this is weighing on Obama's broader nuclear agenda as he heads to Seoul next weekend for the second Nuclear Security Summit. He inaugurated the event earlier in his tenure. Read More