CBS News Correspondent Sharyl Attkisson reports that the W-88 is America's most sophisticated nuclear weapon: a precise, small warhead used on Trident-2 submarine-launched missiles.
There's no evidence that the Chinese have so far been able to build any weapons based on this espionage, but the W-88 is smaller and much more advanced than the nuclear weapons China has relied on for decades.
And while no weapons have been built, The New York Times reported Saturday that China now has the capability to miniaturize its bombs, according to administration officials.
The newspaper reported that, according to officials, the Chinese stole the U.S. nuclear secrets from Los Alamos National Laboratory in New Mexico, enabling them to build and test the smaller bombs during the mid-1990's.
In a pointed dismissal of the charges, Beijing lambasted the Times.
"The report the New York Times printed is very irresponsible. It is also without basis," Chinese Foreign Minister Tang Jiaxuan Tang told a news conference.
But in Washington, some lawmakers were taking the charges seriously.
Senate Intelligence Committee Chairman Richard Shelby said Sunday that Congress would hold hearings as soon as possible to look into the leak of secrets to China in the mid-1980s and the administration's subsequent investigation.
"We've been pushing, we've been prodding the administration to do more, to tighten up security," the Alabama Republican said on the NBC program "Meet the Press."
Although the espionage was believed to have taken place more than a decade ago, it was not detected until 1995, when U.S. analysis of Chinese nuclear test results showed similarities to the W-88, the newspaper said.
By 1996, government investigators identified an American scientist at Los Alamos laboratory as a suspect in the espionage.
They also concluded that Beijing had not stopped stealing secrets from the U.S. government's nuclear weapons laboratories, which had been increasingly open to foreign visitors since the end of the Cold War.
The Times reported that although the White House was informed of the full extent of China's spying in the summer of 1997 -- just before the first American-Chinese summit meeting in eight years -- some American officials said the White House tried to minimize the issue for policy reasons.
CBS News has reported that the congressional report concluded that the theft of the warhead data was the most serious of many security breaches involving China in the last 20 years.
The FBI is still investigating exactly how China obtained the information on the W-88.
Congressional sources say there are still serous security problems at the labs and are fighting to declassify their report. On Friday, the White House disputed that assertion, saying it has tightened security at the weapons labs.
The Clinton administration is pushing to keep much of it secret, citing national security concerns.
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