The jury is still out as to whether Pakistan's nuclear proliferation network, run by scientist Abdul Qadeer Khan, is truly dead. But evidence presented this week, by the London-based think tank, the International Institute for Strategic Studies (IISS), suggests it is not and raises new questions about how that network accommodated Iran's nuclear ambitions.
The report reveals that Mr. Khan "provided Iran with centrifuges, technical designs, components, and an 'address book' of suppliers" and also claims that pieces of Khan's network could still be in operation.
Iran has denied that Pakistani nuclear scientists aided its nuclear program, which it maintains is for peaceful civilian purposes. But the IISS's report suggests that "at least some of Khan's associates appear to have escaped law-enforcement attention and could, after a period of lying low, resume their black-market business."
Their most likely client, the report insinuates, is Iran, which "remains the most active customer in the international nuclear black market."
A crestfallen Khan publicly confessed to his proliferation scheme three years ago, following a Pakistani military-led investigation. That inquiry was prompted by former CIA director George Tenet, who had presented proof of Khan's deceptions to Pakistani President Pervez Musharraf.
Since that time, no one but Pakistan's military has been allowed to question him, despite the international implications of his proliferation network, which sold or traded nuclear-weapons technology to Iran, North Korea, and Libya, and offered information to Iraq in 1990, according to the IISS report.
"Some details concerning exactly what Iran received [from Khan] are still uncertain. What is clear is that Khan's sales helped Iran to make significant advances in its clandestine nuclear programme," said John Chipman, IISS' executive director, in an introductory statement to the report, titled "Nuclear Black Markets: Pakistan, A.Q. Khan and the rise of proliferation networks."
Those revelations are likely to embarrass Pakistan once again, and reheat tensions on this already-shaky dimension of US-Pakistani relations, analysts say.
"It will be a greater embarrassment, put Pakistan in a greater corner," say Ayesha Siddiqa, an independent defense analyst in Islamabad, who added that the pressure from Washington is unlikely to be significant given the US reliance on Pakistan's cooperation in regional politics.
The report comes as lawmakers in Washington, amid growing tension with Iran over its nuclear program, highlighted in March the grave need to get at Khan, who is currently under house arrest and inaccessible to foreign authorities. Khan alone may know the truth about Tehran's weapons program.
But Washington can't hope to reach Khan, who is a national hero in Pakistan, observers here contend. Giving him up is likely to inflame a population already angered by Islamabad's towing of the American line. The more Washington pushes, the more President Musharraf's administration, for reasons of political stability, will have to refuse, many say.
That thought troubled many at a congressional hearing last month.
"We have only purported information from Khan passed to us by the government of Pakistan, a government which in one breath places him under house arrest and in the next celebrates him as a national hero," Rep. Gary L. Ackerman (D) of New York told a hearing on March 21 of the House Foreign Affairs Committee on US policy toward Pakistan.
The IISS's report favorably notes that Pakistan took steps to neutralize Khan's immediate network and to safeguard its nuclear weapons.
But in a statement Wednesday in London, Mr. Chipman of IISS, said that "there are still too many unanswered questions about the role Pakistani technology played in aiding nuclear programs in Iran and North Korea for other countries to conclude that Pakistan has done all it can to account for Khan's activities."
Pakistan maintains that the results of its investigation were shared with the relevant American and international authorities. And some observers argue that, because Pakistan is not a signatory to the Nonproliferation Treaty, it has no obligation to produce Khan or his confession.
"Neither Khan nor Pakistan has broken any international laws," says Shireen Mazari, the director-general of the Institute for Strategic Studies, a government-funded think tank in Islamabad. "All the cooperation we've given has been voluntary."