|World leaders are meeting in Washington with a view to stop groups like
al-Qaeda acquiring nuclear materials [AFP]
Leaders and representatives of 47 nations are in Washington DC for a nuclear summit that has the stated aim of making the world safe from nuclear terrorism.
Barack Obama, the US president, who is hosting the two-day conference, has framed it as a key part of his broader agenda for ridding the world of nuclear weapons, and preventing weapons-grade material from falling into the hands of terrorists, which he says would present the greatest threat to the world.
"Two decades after the end of the Cold War, we face a cruel irony of history - the risk of a nuclear confrontation between nations has gone down but the risk of a nuclear attack has gone up,'' Obama said on Tuesday.
Al Jazeera spoke to experts to determine how real the threat might be.
MJ Gohel, a terrorism specialist at the Asia Pacific Foundation, an independent intelligence think-tank based in the UK, told Al Jazeera that there is real danger of groups like al-Qaeda building or obtaining an atomic bomb.
"Al-Qaeda has for a long time maintained a weapons of mass destruction committee and it, and affiliated terror groups, are determined to obtain chemical, biological, radiological, and nuclear material for the purposes of launching devastating mass casualty atrocities by targeting crowded cities," Gohel said.
"Nuclear terrorism is unfortunately a realistic possibility. Though terror groups themselves may not have the technical knowledge or equipment to produce highly enriched uranium [HEU] or plutonium, it would nevertheless be possible for them to obtain these materials from poorly guarded nuclear facilities.
"Only a small quantity of HEU or plutonium would be needed to assemble a crude device, often referred to as a dirty suitcase bomb, and such a bomb if detonated in the heart of a city would have catastrophic consequences," he said.
But Robert Grenier, a former senior counter-terrorism official at the CIA, said that the probability of al-Qaeda actually acquiring a nuclear weapon is low.
However, he said the impact of such an acquisition would be so devastating that much greater attention should be focused on the problem.
"In terms of the threat of al-Qaeda's intention to acquire nuclear material I think the threat is very real.
"To the best of my knowledge they have never come close to actually getting their hands on any significant quantity of nuclear materials, but given the intention, a certain amount of global reach and the fact that a significant quantity of nuclear materials leaked out in the past and could leak out in the future, there is great concern about what al-Qaeda could do," he said.
Poorly guarded materials
That concern may be compounded by the presence of poorly guarded nuclear materials across the globe.
Experts believe there are about 500 tonnes of plutonium and 1,600 tonnes of highly-enriched uranium scattered around the world.
In January, police in the north Brazilian state of Amapa unearthed a cache of 450kg of enriched uranium ore.
Brazil's nuclear capabilities are considered the most advanced in Latin America. The country runs its single nuclear power plant with two reactors, while a third is under construction.
But Brazil, like many other countries, is not subject to international scrutiny over its nuclear programme, John Large, an independent nuclear engineer and analyst, told Al Jazeera.
He said the International Atomic Energy Agency (IAEA) should be leading the charge to rid the world of such loose nuclear material.
"It should be subject to international accord on how the materials are to be recovered and safeguarded."
He said security for nuclear material is very poor, especially in Russia and the former Soviet Union, which he said had "a very bad accounting system".
In 1996, Muslim fighters from the breakaway province of Chechnya planted, but did not detonate, a dirty bomb in Moscow's Izmailovo park.
The bomb consisted of a deadly combination of dynamite and one of the highly radioactive by-products of nuclear fission - Cesium 137.
"Nuclear terrorism is unfortunately a realistic possibility"
MJ Gohel, terrorism specialist at Asia Pacific Foundation
Large, the nuclear analyst, indicated that threats such as these could be what has prompted the US to hold its nuclear security summit.
"I suspect due to [US President Barack] Obama putting so much emphasis on terrorism during this conference that the US has detected a significant threat," he said.
"A dirty bomb going off in an urban area would create considerable panic. Even if there was no loss of life, the cost of the clean up of contamination would be huge, as well as people being worried to say for example - go back to work in that area."
In 2008, Jose Padilla, a US citizen, was sentenced to 17 years in prison for his part in a 2002 al-Qaeda plot to detonate a radioactive dirty bomb within the United States.
And in 2006 in Britain, Dhiren Barot was sentenced to life in prison for his involvement in an al-Qaeda plot to kill thousands of people in Britain and the US. Although police admitted that Barot was not close to making a dirty bomb, he was accused of trying to do so.
Cause for concern
But perhaps a greater cause for concern has come not from poorly guarded nuclear materials, but existing nuclear weapons.
Terrorism specialist Gohel told Al Jazeera that Pakistan's nuclear assets were the biggest cause for concern "because [the country] is in turmoil, often facing bankruptcy and dependent on foreign aid".
"Intelligence is aware that Pakistani nuclear facilities are not only under threat from the powerful Taliban and jihadist groups based in that country but, very worryingly also, Pakistani nuclear scientists have been known to have met with Osama bin Laden, the al-Qaeda leader, with whom they have had shared ideological leanings," he said.
However, Grenier, the former CIA official, told Al Jazeera that Pakistan is far from a situation where weapons could fall into the wrong hands.
"There is some concern about insiders in Pakistan who have access to nuclear materials being radicalised and getting involved in some sort of conspiracy [against the government] but I think that the threat is less than that of an overall destabilisation of the government," he said.
"If the government of Pakistan were to fall, if militancy were to grow to such a degree that the institutions of the country were to fall apart, perhaps we could see this happening."