After the 11 September attacks, the US provided Pakistan with information that some of its military officers and scientists involved in Pakistan's nuclear weapons program were linked to al Qaeda or had been contacted by al Qaeda. Pakistani President Musharraf ordered all of the suspects identified by the US relieved from duty and his arsenal of about 36 nuclear weapons relocated to a new and more secure facility. The US reportedly provided some unofficial suggestions on ways to improve nuclear security. Two of Pakistan's top nuclear scientists, Choudhry Abdul Majid and Sultan Bashiruddin Mahmood, were arrested by Pakistani police based on US intelligence data provided to Musharraf.--Stephen V Cole