Hugh Pickens writes: "BBC reports that Rolf Mowatt-Larssen, a former investigator with the CIA and the DOE who led US efforts to determine whether al-Qaeda possessed a nuclear bomb in the wake of 9/11, says there are three headlines that keep him awake at night: Pakistani 'loose nukes' in the hands of terrorists, North Korea supplies terrorists with nuclear bombs, and Al-Qaeda launches nuclear attack. While the good news is that Mowatt-Larssen thinks "the odds are stacked against" terrorists acquiring a nuclear bomb, the low probability has to be weighed against the awfulness of the consequences. In Mowatt-Larssen's view, there is "a greater possibility of a nuclear meltdown in Pakistan than anywhere else in the world" because the region has more violent extremists than any other, the country is unstable, and its arsenal of nuclear weapons is expanding. While Mowatt-Larssen says the possibility of a Taliban takeover is a "worst-case scenario," Al-Qaeda's experience on the nuclear black market has taught its planners that its best chance lies in constructing an "improvised nuclear device (IND)," using a quantity of plutonium or 25kg- to 50kg of highly enriched uranium (HEU), the size of one or two grapefruits. HEU is held in hundreds of buildings in dozens of countries. "Security measures for many of these stocks are excellent, but security for others is appalling," according to a report published in 2008 by the Nuclear Threat Initiative and there is no global inventory of either material, so no-one can be sure how much has gone missing over the years. "It is a stark and worrying fact, therefore, that nuclear materials and weapons around the world are not as secure as they should be," writes Ian Kearns, Research Director of the British-American Security Information Council, adding that the future of nuclear security hangs on this week's summit in Washington."