With the optimism sparked by President Obama’s vision for a nuclear weapons-free world having faded, the Bulletin of the Atomic Scientists’ symbolic ‘Doomsday Clock’ was moved one minute closer to midnight yesterday. The group of scientists shifted the minute hand on the clock from six minutes to five minutes to midnight, moving it back to its position from 2007 to 2010. The central reason was flagging momentum for cuts to the worldwide stockpiles of nuclear weapons and slow progress in addressing climate change, scientists from the group said yesterday. “The path toward a world free of nuclear weapons is not at all clear, and leadership is failing,” said Jayantha Dhanapala, a member of the group’s Board of Sponsors and the former Sri Lankan ambassador to the United States. He noted one positive—ratification of the New START Treaty by the United States and Russia—but he suggested that stagnation involving the Comprehensive Test-Ban Treaty and Fissile Material Cutoff Treaty overshadowed any disarmament or nonproliferation progress.