But the event eventually led to the 700-page Congressional report into how China targeted the United States' nuclear secrets - and how it appears to have got away with enough of them to close a huge technological gap with a superpower.

The report, chaired by Republican Representative Chris Cox, was completed in December last year with committee members unanimously agreed on its content.

But its release was delayed amid wrangling between the White House and Capitol Hill over what the public report would say.

The committee began by investigating allegations that China attempted to transfer commercial technology to nuclear purposes.

But it quickly expanded to probe wider allegations of systematic targeting of scientists and nuclear laboratories over 20 years.

China has rejected espionage charges, alleging that its critics in the US are deliberately trying to harm Sino-US relations.

Rocket goes up

Following the failed launch of the 1996 commercial rocket, representatives from the satellite's makers, Loral Space Systems, and another company, Hughes Electronics, worked with Chinese scientists to improve the launch reliability.

Lagging behind: US was 15 years ahead of China

The New York Times newspaper was the first to allege that the two companies may have unwittingly passed on 'dual-use' technologies to China.

Dual-use technology is so advanced that it can be employed in weapons programmes - it is the kind of technology that the United Nations has been attempting to keep out of the hands of Iraq's Saddam Hussein.

The Loral controversy led to wider allegations that China was buying technology vital for an improved nuclear weapons programme.

Using public information and legitimate contracts for everything from communications systems to powerful computers, China is said to have breached America's national security by slowly obtaining pieces of a nuclear weapons jigsaw.

1980s: What did China learn?

Los Alamos National Laboratory, operated by the University of California for the US Department of Energy, is the heart of America's nuclear research programme.

Detonator: US fears technology will fall into wrong hands

While it declares that its mission is to "reduce the global nuclear danger", it has been accused of huge lapses in security which led to the most sensitive information in the US nuclear programme being spirited away on computer disks.

China is said to have begun to steal secrets from the New Mexico research centre in the 1980s, with allegations focused on the highly sophisticated W-88 miniature warhead, an essential part of the modern nuclear arsenal.

In the run up to the release of the congressional report, various leaks to the US media suggested that China had probably obtained information on seven similar weapons designs which effectively closed the 15-year gap between the two countries.

Speaking before the release of his report, Representative Chris Cox told Fox News TV that he expected to see China testing intercontinental ballistic missiles with warheads based on US technology within a year.

Scientist suspected

Charges of incompetence against Los Alamos were compounded when a Taiwanese-born computer scientist, Wen Ho Lee, was sacked in March.

Wen Ho Lee: Said to have transferred files

Mr Lee had failed a lie detector test as part of a three-year investigation into security at the establishment, though he has not been charged with any crime.

Information now believed to be in Beijing's hands is said to include data for the neutron bomb - a nuclear device which detonates with minimum heat but maximum radiation, leaving cities intact but populations dead.

The sacking exacerbated tensions with Beijing with Foreign Minister Tang Jiaxuan accusing the New York Times' reports of espionage as "extremely irresponsible and unfounded".

Legacy of espionage

The BBC was informed earlier this month that Wen Ho Lee has reportedly admitted placing 1,000 of the most sensitive Los Alamos files onto an unclassified computer which was then accessed by the Chinese.

These so-called "legacy codes" are the core of American and British nuclear research, spanning five decades of tests.

A further scientist, Chinese-born Peter Lee, is accused of handing over technology that was being developed to detect nuclear submarines from the air.

Jon Kyl, a member of the Senate Intelligence Committee and the China espionage report, told the BBC that the Chinese could now track British and American submarines - compromising their main function as a deterrent.

The key allegation is that every administration from Jimmy Carter to Bill Clinton has failed to work out what China has been trying to do until it is too late.