Pakistan has refused US demands to talk to Abdul Qadeer Khan, whose black market network sold nuclear technology to Iran and North Korea The security ring surrounding Abdul Qadeer Khan’s sprawling mansion at the foot of Margalla hills in Islamabad has visibly tightened in recent weeks. Uniformed soldiers with machine guns block all access to the property and scrutinise every passing vehicle. Mr Khan, the "Father" of Pakistan’s nuclear bomb, has been under house arrest since February 2004 when he confessed to operating an international bazaar for nuclear technology, and spends his days confined with his Dutch wife, Henny, inside...