But the details are complex, confusing, and the effects largely unproved. This is a tale of two nuclear projects, two US laboratories, and two Dr Lees. The first Dr Lee, Wen Ho Lee, worked at the US National Laboratory at Los Alamos for almost 20 years, specialising in nuclear weapons design. After suspicions about his loyalties, the Taiwan-born scientist was dismissed two months ago, but the proof needed for prosecution, according to the FBI, is lacking and he will not apparently be prosecuted.
According to revelations in The New York Times, Wen Ho Lee downloaded hundreds of top-secret files from his own secure computer system on to an unclassified computer, where they may have been accessed by the Chinese. Among the data transferred, according to US officials, were details of British nuclear tests. The accessing is supposed to have been done by Chinese intelligence.
Wen Ho Lee's name was first mentioned in connection with China's apparent acquisition of US designs for a miniaturised nuclear warhead, which enabled a missile to be armed with multiple warheads. The theft, assumed to have taken place in the mid-Eighties, came to light only when China tested one of the new missiles in 1995, and a close similarity was observed to their US equivalent.
The theft claim precipitated a welter of inquiries, and a security "tsar" is to be appointed to oversee all the US Department of Energy's laboratory security. In announcing the changes the Energy Secretary, Bill Richardson, conceded that China had been spying on US research laboratories for two decades, including the six years of Mr Clinton's presidency.
For Britain, however, it is another laboratory and another Lee who may have done the most damage. A Chinese-born physicist, Peter Lee, was working for a private company, TRW Incorporated, under the auspices of the Pentagon. The technology was developed at the Lawrence Livermore national laboratory in California, where Dr Lee was working on a classified British-American project to develop radar that would be able to detect submarines from the air. In May 1997, according to US officials, Dr Lee passed the information to Chinese scientists during a two-hour lecture in Peking.
Some details of the case emerged from a US Senate intelligence sub-committee report published this week, and Senator Jon Kyl was quoted as saying that China now had the technology to detect British and American nuclear submarines. Britain's only nuclear deterrent is the Trident submarine.
Dr Lee pleaded guilty to filing a false statement about his trip to China in 1997 and to divulging classified data on laser technology to Chinese scientists during a trip to China 12 years before.
But the Senate intelligence sub-committee report acknowledged that much of the information used by China in weapons development could have been obtained from published sources. The proliferation of academic exchanges between top scientists from China and the US has opened up much previously classified information. The growing practice of commissioning defence work from private research companies blurs responsibilities further.
Even if the spying allegations are true, there is no consensus on the extent of the damage. With the miniaturised nuclear warhead technology, experts say China may have recouped between 10 and 15 years of its research lag with the US.
Nick Cook, a military group specialists with Jane's, said the leak about nuclear submarines was potentially devastating.
But Dr Eric Grove of the Centre for Security Studies at Hull University said the theft would be more embarrassing than dangerous. Even if the Chinese were able to detect a submarine, he said, they lacked the expertise to do anything about it. Such a project, he said, would "probably take up the entire Chinese defence programme".Reuse content