World leaders from 47 countries are descending on Washington this week for an unprecedented summit to discuss what is arguably one of the most pressing global security questions: What can be done to prevent a nuclear weapons attack by terrorists?
White House officials say the focus of the summit is to trigger a common sense of urgency about the threat of nuclear weapons from terrorists, as well as nation states such as Iran and North Korea, and to devise a plan for individual countries to better secure their nuclear materials and access to nuclear technology.
"We know that organizations like al Qaeda are in the process of trying to secure a nuclear weapon -- a weapon of mass destruction that they have no compunction at using," the president said Sunday.
"If there was ever a detonation in New York City, or London, or Johannesburg, the ramifications economically, politically, and from a security perspective would be devastating," he said.
Former CIA Agent Rolf Mowatt-Larssen has been working on nuclear threats since the Cold War. He recalls the moment when he first realized that the notion of terrorists procuring or manufacturing nuclear weapons wasn't so far-fetched.
"'Terrorists, men in caves can't do this,' was more or less what I thought coming in as a veteran intelligence officer and it was maybe a year or two later when I realized, 'Oh my God, these guys are actually trying to do this,'" Mowatt-Larssen said.
Speaking on ABC's "This Week" today, Secretary of State Hillary Clinton said the goal of the summit is "to have everyone sign off on an agreed upon work plan that will enable us to begin to try to tie up these loose nukes ... to make sure they don't fall into the wrong hands."
The administration has pledged to try to "secure all vulnerable materials" within four years.
Mowatt-Larssen says the four-year timeline set by the administration may be an unrealistic goal -- but it's a necessary one.
"Time is not on our side," he says. "As long as you have terrorist groups and others with the intent -- and not just groups, Iran Korea and other states -- the world's got to treat the nuclear threats that we face with a much greater sense of urgency than we have in the last few years.
"Part of the goal of the nuclear security summit is to focus on the threat from nuclear terrorism. And we don't believe the threat from nuclear terrorism comes from states. Our biggest concern is that terrorists will get nuclear material," Clinton said.
However, she added that Iran's and North Korea's nuclear programs were also dangers.
"We fear North Korea and Iran, because their behavior as -- the first case, North Korea being -- already having nuclear weapons, and Iran seeking them, is that they are unpredictable. They have an attitude toward countries like Israel, like their other neighbors in the Gulf that makes them a danger," Clinton said.
Just days ago, Iran announced it was installing more advanced centrifuges at its main nuclear plant in Natanz.
White house officials say this summit will set in motion a series of follow-up meetings and action plans for individual countries.
It's the first step in a long process to curtail nuclear proliferation as articulated by President Obama when he won the Nobel Peace Prize last year.