U.S. President Barack Obama has urged world leaders to do more to secure vulnerable nuclear facilities to prevent “madmen” like Islamic State from getting a nuclear weapon or a radioactive “dirty bomb.”
Obama made the appeal on April 1 in Washington at the end of the two-day Nuclear Security Summit.
Obama hosted more than 50 world leaders for his fourth and final summit focused on efforts to lock down atomic materials to guard against nuclear terrorism, which he called "one of the greatest threats to global security" in the 21st century.
Obama said no group had succeeded in obtaining bomb materials but that Al-Qaeda had long sought them, and he said actions by Islamic State militants in Paris and Brussels had recently raised similar concerns.
Obama said the required 102 countries have now ratified an amendment to a nuclear security treaty that would tighten protections against nuclear theft and smuggling.
"We have measurably reduced the risks," he said.
But he acknowledged that with roughly 2,000 tons of nuclear material stored around the world, "not all of this is properly secured."
Obama, wrapping up the summit, said leaders had agreed to strengthen their nuclear facilities against cyberattacks, something that outside experts see as a major weak point.
Despite their calls for further action, the roughly 50 leaders assembled announced that this year's gathering would be the last of its kind.
Obama inaugurated the first Nuclear Security Summit nearly six years ago, after a 2009 speech in Prague laying out the goal of a world free of nuclear weapons.
Among the notable absentees was Russia, whose relations with the West have soured over its actions in Ukraine among other issues.
Obama made no public mention of Russian President Vladimir Putin as a summit no-show.
But he did say that because of the Russian's leader's emphasis on building up his military, there was unlikely to be any further deals for reducing the two countries' vast nuclear weapons stockpiles during what is left of the Obama presidency.