North Korea's nuclear test has once again revived the disturbing question of the involvement of Pakistan's rogue scientist, Dr Abdul Qadeer Khan, in proliferating atomic know-how to Pyongyang.
Dr Khan, feted for decades as the "father of Pakistan's atom bomb", had admitted on television in February 2004 to selling nuclear secrets, including hardware and blueprints to North Korea as well as to Libya and Iran, in violation of international norms.
Dr Mohammad ElBaradei, head of the UN's nuclear watchdog body, the International Atomic Energy Agency (IAEA), had referred to Dr Khan's disturbing prolific nuclear commerce as a "nuclear Walmart" following startling revelations of the Pakistani scientist's proliferation activities.
Dr Khan (71), who is under house arrest in Islamabad and was recently diagnosed with cancer, has not been questioned by either the IAEA or the US, both keen to obtain information about North Korea's and Iran's nuclear programmes. Dr Khan is believed to have made several unpublicised trips to Pyongyang.
But President Pervez Musharraf's government remains determined to block all outside access to the scientist, fearful of what he may reveal of the military's alleged role in his activities. Pakistani lawmakers in June rallied behind the disgraced Dr Khan, passing a resolution in the senate opposing US demands for the scientist's further interrogation as an attack on Pakistan's sovereignty.
Meanwhile, Pakistan, the last country to test an atomic weapon, in May 1998, has deplored the North Korean test and warned that it would destabilise the region. Some analysts, however, speculate that North Korean scientists were present during Pakistan's 1998 nuclear tests and that Pyongyang could have obtained a tested bomb design from Islamabad or from Pakistani scientists.
According to retired senior Indian intelligence officer B Raman, North Korea's assistance to Pakistan in developing its missile potential was a "quid pro quo" for the latter's assistance in helping Pyongyang build its military nuclear capability.
Citing Pakistani intelligence assets, Mr Raman states that this symbiotic co-operation took place in the mid-1990s after a retired Pakistani major general, charged with the clandestine procurement of nuclear and missile technologies for Islamabad, was posted to Pyongyang.
During his tenure, the two-star officer allegedly co-ordinated the secret shipping of long-range North Korean missiles to Pakistan as well as training scientists from Pyongyang in Pakistani nuclear facilities between 1992 and 1996. "This nexus was first established during the second tenure of prime minister Benazir Bhutto till 1996, when she made a clandestine visit to Pyongyang, and was subsequently nursed by her civilian and military successors," Mr Raman declares.