Pakistan is in danger of "losing control of part of its nuclear arsenal" to terrorists, according to a new report published by the Stockholm International Peace Research Institute (SIPRI). In its report published on Tuesday, the global think-tank said that India and Pakistan are "expanding their capacity to produce fissile material for military purposes." The report said that the world's eight nuclear powers - Britain, China, France, India, Israel, Pakistan, Russia and the US - possess more than 20,500 warheads.