 Hecker later testified before the United States Congress that while North Korea seems to have successfully extracted plutonium from the spent fuel rods, he saw no evidence at the time that they had actually produced a workable weapon.In 2007, the former senior scientist of Pakistan, Dr. Abdul Qadeer Khan claimed that North Korea's nuclear program was well advanced before his visit in 1993 with Benazir Bhutto, former prime minister.In September 2004, though, North Korean officials announced they had successfully processed Yongbyon plutonium into a workable nuclear deterrent.