U.S. President Barack Obama urged world leaders on Friday to do more to safeguard vulnerable nuclear facilities to prevent "madmen" in groups like the Islamic State from getting their hands on an atomic weapon or creating a radioactive "dirty bomb."
Speaking at a nuclear security summit in Washington, Obama said the world faces a persistent and evolving threat of nuclear terrorism despite progress in reducing such risks. "We cannot be complacent," he said.
Obama said no group has succeeded in obtaining bomb materials but that al-Qaida has long sought them, and he cited actions by Islamic State militants behind recent attacks in Paris and Brussels that raised similar concerns.