Washington, United States (AFP)—-World leaders reaffirmed their commitment to keep nuclear weapons out of the hands of extremists on Friday but warned that the threat is “constantly evolving.” “More work remains to be done to prevent non-state actors from obtaining nuclear and other radioactive materials, which could be used for malicious purposes,” the leaders said, in a joint statement at the Nuclear Security Summit in Washington. United States President Barack Obama invited dozens of world […]