WASHINGTON -- World leaders are wrestling this week with the prospect of terrorists unleashing a nuclear attack on a major Western city.
Preventing militant groups such as the Islamic State from obtaining nuclear materials is the central focus as President Barack Obama hosts leaders from roughly 50 countries for a nuclear security summit starting today. Despite three previous summits and six years of Obama's prodding, security officials warn that the ingredients for a nuclear device or a "dirty bomb" are alarmingly insecure.
"We know that terrorist organizations have the desire to get access to these raw materials and to have a nuclear device," said Ben Rhodes, Obama's deputy national security adviser. Still, the White House said there was no indication of an imminent plot.
Decades after the Cold War, the threat of a nuclear war between superpowers has given way to growing concerns about nonstate actors, including Islamic State and al-Qaida offshoots operating in North Africa and in Yemen and Saudi Arabia. Although the U.S. and its allies still worry about North Korea, Obama believes the threat posed by Iran has subsided because of last year's nuclear deal, leaving extremist groups among the likeliest perpetrators.
The havoc such an attack could wreak in an urban area such as New York or London is concerning enough that leaders scheduled a special session on the threat during the two-day summit. U.S. officials said the leaders would discuss a hypothetical scenario about a chain of events that could lead to nuclear terrorism.
"The key question for this summit," said Matthew Bunn, a nuclear expert at Harvard and a former White House science adviser, "is whether they'll agree on approaches to keep the improvements coming."
Those concerns have taken on heightened significance after the March 22 attacks at a Brussels airport and subway station. Last year, authorities searching the apartment of two brothers linked to earlier attacks in Paris found video taken of a senior Belgian official at a Belgian nuclear waste facility. The brothers were part of the Islamic State cell that went on to strike Brussels; both died in the attacks.
On the summit's sidelines, Obama planned to meet with the leaders of China, South Korea and Japan, who all share U.S. concerns about North Korea's nuclear program.
Other key players, however, will be missing. Russian President Vladimir Putin has refused to attend, as Moscow said the United States was trying to take control of the nuclear cleanup process.
Prime Minister Nawaz Sharif of Pakistan, which has an arsenal of small nuclear weapons, canceled his trip after an Easter bombing in Lahore killed 72 people.
The summit also comes as Japan is shipping some 700 pounds of plutonium to South Carolina. Gov. Nikki Haley has asked the federal government to stop or reroute the shipment to the Savannah River Site.
On Tuesday, Haley said U.S. Energy Secretary Ernest Moniz agreed to relocate 6.6 tons of plutonium currently at the site to a facility in New Mexico that should be operational by the end of this year.
Calling the deal a win, she also pointed out her continuing lawsuit against the Department of Energy over an unfinished project to process weapons-grade plutonium also stored at the site into commercial reactor fuel.
"We will continue to watch this process carefully, as the Department of Energy has not lived up to promises made in the past," Haley said in a statement. "We will not back down from our lawsuit until the [the department] pays the $1 million a day fine they are required to under federal law."
Energy officials didn't immediately return a message seeking comment.
Attack scenarios
Some 2,200 tons of highly enriched uranium and separated plutonium being used in civilian or military programs could be turned into a nuclear bomb if stolen or diverted, the White House said. And fewer than half of the countries participating in the summit have even agreed to secure their sources of radiological material needed for a dirty bomb.
"The policies are moving in the right direction," said Joe Cirincione, who runs the nuclear security group Ploughshares Fund. "But when you're fleeing a forest fire, it's not just a question of direction, it's a question of speed."
Nuclear-security experts say there are four potential scenarios for a nuclear-related attack by an extremist group. Some are more likely than others.
The most devastating but improbable scenario involves a group stealing a fully functional bomb from a nuclear-armed country.
Easier to pull off would be for the Islamic State or another group to obtain fissile material such as highly enriched uranium, then turn it into a crude nuclear device delivered by truck or ship. A third possibility is that extremists could bomb an existing nuclear facility, such as the Belgian waste plant, spreading highly radioactive material over a wide area.
The most likely scenario that security experts fear is that a group could obtain radioactive material, such as cesium or cobalt, for a dirty bomb that could be carried in a suitcase. Those materials are widely used in industrial and academic settings as well as in hospitals to irradiate blood, with no consistently applied security standards across the globe.
Fewer than half of the countries that attended the last nuclear summit in 2014 pledged to secure such materials, and they in turn represent less than 15 percent of the 168 nations belonging to the International Atomic Energy Agency.
Unlike a nuclear bomb, the only people killed instantly by a "dirty bomb" would be those close to the blast site. But the blast could spread cancer-causing substances over a vast area, triggering panic and evacuations.
Detonated in a major city, a dirty bomb could cause tens of billions of dollars in economic damage, said Andrew Bieniawski, a former U.S. Energy Department official now with the Nuclear Threat Initiative, a private advocacy group in Washington that tracks nuclear weapons and materials. People and businesses would have to be relocated -- potentially for years -- while the contamination is cleaned up. Few would be inclined ever to go back, a reality on display in Chernobyl, Ukraine, decades after the 1986 accident.
Uranium danger
Reducing the threat of nuclear terrorism has been a persistent theme for Obama, who won the Nobel Peace Prize after emphasizing nuclear disarmament. Four months into his presidency, Obama warned in a much-cited speech in Prague that nuclear weapons were "the most dangerous legacy of the Cold War."
Rhodes, the security adviser, told reporters Tuesday that the administration's overall efforts had made it "harder than ever before for terrorists and bad actors to acquire nuclear material."
And while the administration succeeded in getting more than a dozen countries to give up their civilian stockpiles of highly enriched uranium, a main fuel of atomic bombs, the Nuclear Threat Initiative said in another report that some 25 nations still had such materials -- enough for thousands of nuclear weapons.
The report called highly enriched uranium "one of the most dangerous materials on the planet," warning that an amount small enough to fit in a 5-pound bag of sugar could be used to build a nuclear device "with the potential to kill hundreds of thousands of people."
The results of previous summit meetings have ranged from treaty ratifications to the establishment of more than a dozen training centers around the globe where guards, scientists, managers and regulators sharpen their skills at preventing atomic terrorism.
The biggest wins have been the removal of all highly enriched uranium from 12 countries, including Ukraine, Austria, Chile, Hungary, Libya, Mexico, Turkey and Vietnam. The material was mostly reactor fuel, but officials said terrorists could have turned it into least 130 nuclear weapons.
Critics of the summit process point to vague communiques that seem to have done little to drive hard decisions.
But Laura Holgate, Obama's top adviser on nuclear terrorism, told reporters Tuesday that this week's meetings would address exactly that question: "How do you sustain the momentum to the summit after the summit ends?"
Information for this article was contributed by Josh Lederman and Meg Kinnard of The Associated Press and by David E. Sanger and William J. Broad of The New York Times.
A Section on 03/31/2016