A new book confirms what has to be one of the more unusual exchanges of nuclear information outside of outright spying and helps explain how Pakistani nuclear weapons knowledge made its way to North Korea.

In late 1993 Benazir Bhutto, then prime minister of Pakistan, carried critical nuclear data on CDs in her overcoat to Pyongyang in 1993 and brought back North Korea's missile information, according to a new political biography, "Goodbye Shahzadi," by veteran Pakistani journalist Shyam Bhatia.

Bhutto was murdered last December after returning to Pakistan from exile in order to win an election once again as prime minister.

Although it has been mentioned previously in other books, this episode is notable, if only for the fact that Bhutto was, essentially, acting as a female James Bond. Her visit took place when she was prime minister for the second time and had agreed to visit North Korea to ask for No-dong missiles, at the request of A.Q. Khan, the father of Pakistan's nuclear weapons program. During a state banquet of chestnuts and steamed fish, the book maintains that Bhutto stammered with nerves as she requested a favor from North Korea's founding father, Kim Il-Sung. She left with a bag of computer disks to pass on to her military.

That was not the first time Bhutto had dealings involving Khan. She said in a 2004 interview with Bhatia, "I first came across him in 1988 when he came to see me with Munir -- Munir Ahmad Khan, head of the Pakistan Atomic Energy Commission. They seemed like government servants ready to carry out government orders."

In regard to the proliferation publicly admitted by Khan at the beginning of 2004, Bhutto said, "I suspect it was (current Pakistani President Pervez) Musharraf because (during) the time I am looking at, both Libya and North Korea were squarely under Musharraf's watch as chief of army staff and chief executive of Pakistan."

Ironically, a few months before she was killed Bhutto said that, if returned to power, she would allow U.N. inspectors but not Western powers, and especially not the United States, to question Khan.

According to Bhatia's book, in 1993 the central question was how the barter for enrichment of uranium -- a process A.Q. Khan had mastered -- for missiles from North Korea could be carried out.

"Pakistan was under the spotlight as it had never been before, with India, Russia and the secret services of the West monitoring every nuance of the country's military research," the book says.

Bhatia details cooperation between Pakistani and North Korean nuclear scientists, which seems to confirm what many in the West suspected -- that an Islamabad-Pyongyang axis in proliferation existed that was allegedly aided by Beijing.

Confronting growing international pressure to shut down their plutonium facilities, North Korean scientists looked to Pakistan for help to develop a parallel enrichment program. Subsequently, after Bhutto's visit, Khan and colleagues from Pakistan became regular visitors to North Korea. By 1998 there were nine military flights a month ferrying military officers and scientists between Islamabad and Pyongyang.

The significance of Bhutto's North Korean trip is that the transfer of nuclear knowledge was not some independent operation carried out at Khan's behest. Instead it was done with the full knowledge and approval of the Pakistani government.

Such approval would explain why Musharraf vehemently opposed making Khan available for further questioning. Among other things, it would show that Musharraf was lying when he wrote in his memoir, "In the Line of Fire," that Khan provided "nearly two dozen" prototype centrifuges suitable for uranium enrichment to North Korea -- a charge flatly denied by Pyongyang, and for which there has never been any proof provided.

It would also further debunk the idea that Khan was some sort of rogue operator acting on his own when it came to exporting nuclear technology and knowledge. As Bhutto said in 2004, "He couldn't even leave the country without somebody watching everything he did, and to accept that he ran an international operation -- that Israeli businessmen were involved, Indian businessmen were involved, that parts were coming from South Africa and Malaysia without anyone knowing -- is unbelievable."

(David Isenberg is a national security affairs analyst. He is an adjunct scholar with the Cato Institute and a research fellow at the Independent Institute.)