The founder of Pakistan's nuclear bomb program asserts that the government of North Korea bribed top military officials in Islamabad to obtain access to sensitive nuclear technology in the late 1990s.
Abdul Qadeer Khan has made available documents that he says support his claim that he personally transferred more than $3 million in payments by North Korea to senior officers in the Pakistani military, which he says subsequently approved his sharing of technical know-how and equipment with North Korean scientists.
Khan also has released what he says is a copy of a North Korean official's 1998 letter to him, written in English, that spells out details of the clandestine deal. The letter, which US officials said they had not seen previously, is dated July 15, 1998, and marked "Secret."
Some Western intelligence officials and other experts have said that they think the letter is authentic and that it offers confirmation of a transaction they have long suspected but could never prove. Pakistani officials, including those named as recipients of the cash, have called the letter a fake.
The North Korean government did not respond to requests for comment about the letter.
The Pakistani Embassy in Washington declined to comment officially. But a senior Pakistani official, who spoke on the condition of anonymity "to avoid offending" Khan's supporters, said the letter "is clearly a fabrication.
Nevertheless, if the letter is genuine, it would reveal a remarkable instance of corruption related to nuclear weapons. US officials have worried for decades about the potential involvement of elements of Pakistan's military in illicit nuclear proliferation, partly because terrorist groups in the region and governments of other countries are eager to acquire an atomic bomb or the capacity to build one.
Because the transactions in this episode would be directly known only to the participants, the assertions by Khan and the details in the letter could not be independently verified by The Washington Post.
A previously undisclosed US investigation of the corruption at the heart of the allegations - conducted before the letter became available - ended inconclusively six years ago, in part because the Pakistani government has barred official Western contact with Khan, US officials said.
Although US officials disagreed for years about North Korea's uranium-enrichment capability, the dispute was settled in November when the Pyongyang government invited Siegfried Hecker - a metallurgist who formerly directed a US nuclear weapons laboratory - to see a newly renovated building at Yongbyon that housed more than 1,000 enrichment centrifuges.
"The combination of the Pakistani design, the Pakistani training and the major [Pakistani] procurement network they had access to" allowed North Korea to "put the pieces together to make it work," Hecker said in an interview.
(In exclusive partnership with The Washington Post)