A traumatic scene opens up. From a silent abettor of Pakistan's nuclear strivings in the eighties and early nineties, American policy-making has made a sharp u-turn. It has become jittery over the fate of the Pakistani nuclear stockpile and wants to position itself in the role of a policeman watching over Pakistan's nuclear weapon facility. Why has this happened - what has brought about this sharp juxtaposition? Most important of all is the question: can the US force itself on Pakistan in this role of a nuclear policeman? We have here the proverbial riddle wrapped in an enigma. In attempting to answer these questions, much of the hyperbole surrounding Pakistan's nuclear capability has to be pruned. Pakistan, it has to be recognised, is in an early stage of acquiring nuclear capability. It cannot, on the strength of its indigenous capability, construct and sustain advanced nuclear projects such as power reactors. Pakistan's nuclear establishment is heavily dependent on foreign collaboration to build and operate such projects. How then has Pakistan been able to build and run the complex nuclear project, the Kahuta centrifuge uranium enrichment facility? Thereby hangs a tale - the A. Q. Khan story. Dr Khan, a competent nuclear metallurgist who worked for three years at the British-German-Dutch centrifuge enrichment plant at Almelo in Holland, was able to build a small-scale centrifuge uranium enrichment facility at Kahuta entirely based on clandestine imports, outside the Pakistan Atomic Energy Commission's meagre infrastructure. Dr Khan was able to copy the Almelo plant's design that he stole while quitting - displaying considerable ability as an organiser and nuclear metallurgist. Himself not a physicist, Dr Khan used the knowledge of the centrifuge plant's design and working during his three-year job at Almelo in Holland. Thus, the Kahuta centrifuge plant was not the product of Pakistan's indigenous nuclear knowhow. The Kahuta story has been kept a secret because it involved clandestine nuclear equipment imports on a massive scale - including basic material such as high quality maraging steel used in a centrifuge plant, which Pakistan is unable to make on its own. Even nuts and bolts of the centrifuge plant cannot use inferior steel. These clandestine imports were from nuclear industries of leading Western countries. Germany, perhaps, topped the list. An entire plant that makes uranium hexaflouride - the basic material for Kahuta - was smuggled out from Frankfurt airport, in parts. Says a BBC report: "Several German companies deceived the authorities and clandestinely exported to Pakistan vital and specialised instruments required for its nuclear programme