S. M. Hali David Albright, Paul Brannan, and Andrea Scheel Stricker of the Institute of Science and International Security (ISIS), in their Op-Ed of December 9, 2009 titled Self-Serving Leaks from the A Q Khan Circle have examined claims made by Simon Henderson in his article Investigation: Nuclear scandal - Dr Abdul Qadeer Khan published in The Sunday Times of September 20, 2009. Later selectively quoted by R Jeffrey Smith and Joby Warrick in The Washington Post of November 13, 2009 in their piece titled A nuclear power's act of proliferation. Simon Henderson's report is based on an allegedly smuggled secret letter in which Dr Khan tells his side of the story. The ISIS investigators refute Khan's assertion that China depended on Pakistan in the early 1980s in making weapon-grade uranium for its growing nuclear weapons arsenal. Using recently "stolen" European gas centrifuge technology, Khan claims he helped China modernise its production of bomb-grade uranium. David Albright et al rebut the claim stating that "China relied on its two gaseous diffusion plants to make its weapon-grade uranium, and its gas centrifuge programme never took off." Casting a shadow of doubt on Dr Khan's contention that he was not alone in the dark deed of nuclear proliferation, despite having issued a signed statement accepting the sole responsibility for it in 2004, the authors state that "Dr Khan's statements should be viewed as non-credible and necessitate verification. He has proven that he is unable to honestly relate the facts fully as he knows them and has many reasons to deceive, obfuscate or suppress the truth." Regarding Pakistan's nuclear programme, the ISIS sleuths affirm that China provided critical assistance to Pakistan's nuclear weapons effort. Without this aid, Pakistan would have likely suffered several more years of delay in obtaining nuclear weapons. Yet, the benefits to China were mostly strategic not nuclear. David Albright warns: "Khan's writings must be approached with a great deal of scepticism, given his well-known denials of any wrong-doing and frequent selective use of the truth. Henderson is well aware of Khan's proclivities. During his journalistic career at the Financial Times, he uncovered several of Khan's shady deals. In the mid-1980s, he was the first to report that China gave Pakistan 50 kilograms of weapon-grade uranium, an important part of the recent Washington Post article." Simon Henderson stresses that Dr Khan was a government official and an adviser with ministerial status even after he retired in 2001. If his dissemination of nuclear secrets was authorised by the government, it could not be illegal and he would enjoy sovereign immunity for his actions. Pakistan is also not a signatory of the Non-Proliferation Treaty (NPT), so its nuclear trades, however reprehensible, were not against international law. ISIS challenges Simon Henderson's contention with the argument that "Henderson's objectivity about Khan was called into question in the early 1990s, when he started to soft-pedal Khan's tales." According to Henderson, he sought Khan's cooperation on a biography that he (Henderson) hoped to write, and frank assessments of the latter's (Khan) statements would unlikely result in that support. This led Henderson to submit an uncritical interview with Khan in the Bulletin of the Atomic Scientists in September 1993. The ISIS investigators doubt the veracity of Dr Khan's claim asserting that the major problems in Washington Post's (and reportedly Khan's) account centre on the nuclear scientist's argument about the importance of the centrifuge plant he built for China and his claim that Pakistan did not use the weapon-grade uranium it acquired from China in its first nuclear weapon. The article quotes from a Khan written document that Pakistani experts were dispatched to Hanzhong in central China, where they helped "put up a centrifuge plant." Khan wrote in the 2003 letter to his wife that "we sent 135 C-130 plane loads of machines, inverters, valves, flow meters, pressure gauges." ISIS counters with the observation that by the early 1980s, China had constructed two relatively large gaseous diffusion plants. In addition, during the early 1980s, China achieved an enormous breakthrough in the enrichment performance at these plants, reducing further the importance of any centrifuge assistance. Any contribution from gas centrifuges is believed to be small. The Chinese centrifuge programme was still in the development stage in the early 1990s. According to a US centrifuge expert, eyewitness who visited a Chinese pilot centrifuge plant in 1990 the Chinese appeared to be still developing centrifuges and had not yet built a large-scale centrifuge plant. By the early 1990s, the Chinese government decided to buy two large-scale centrifuge plants from Russia to supply low enriched uranium for its nuclear power reactors rather than build a centrifuge plant itself. Its own centrifuge programme was cut back substantially after this decision. In the late 1990s, the US expert revisited the Chinese pilot plant and it was no longer working on centrifuges but instead it was dedicated to laser enrichment. With regard to the claim by Dr Khan that he had no need for the Chinese weapon-grade uranium due to an abundance of its own at the time David Albright and company think it is highly unlikely. Given Khan's defensiveness about his legacy, it is not surprising that he would assert this. His reputation relies fundamentally on his claim that he was responsible for making the weapon-grade uranium for Pakistan's first nuclear weapons. If it were established that Pakistan's first two nuclear weapons were fuelled by China's gift, Khan's reputation would suffer and questions about the success of his centrifuge programme would arise. The ISIS punch line comes in its conclusion that the Khan circle's latest media campaign likely centres on his effort to embarrass and paint the Pakistani government as complicit in all of his proliferation activities, and it should be seen as part of his greater effort to shame the government into lifting his freedom of movement restrictions. These stories go to prove that the Occident continues its efforts to rake up the Dr Khan episode and attempt to embarrass Pakistan, and pressurise it into abandoning its nukes. The writer is political and defence analyst.