(AP) -- China has stolen classified information about every currently deployed nuclear weapon in the U.S. arsenal and it is ``exceptionally likely'' that Chinese spying continues to this day, the chairman of a congressional investigating committee said today. Rep. Christopher Cox, R-Calif., also said two U.S. defense companies ignored legal requirements and allowed China to obtain information critical to its ballistic missile program. President Clinton responded by saying his administration was already ``moving aggressively to tighten security'' at America's nuclear laboratories. ``We have a solemn obligation to protect such national security information and we have to do more to do it,'' the president told an audience in Texas. ``I want to assure you and all the American people that I will work very hard with the Congress to protect our national security, to implement the recommendations (of the Cox committee) and to continue our policy of engagement because both of them are in the national interest,'' Clinton said. Cox gave his assessment at a news conference after copies of the unclassified 700-page report were made public. He said the conclusions reached in the unanimous report were supported by additional volumes of classified factual material. The ranking Democrat on the committee, Rep. Norm Dicks of Washington, called the security losses ``one of the worse counterintelligence failures in the nation's history.'' And Republican Rep. Doug Bereuter of Nebraska, a former Army counterintelligence officer, added, ``What is so gravely disappointing is the fact that we had the incompetence, laxity, naivete to let this happen.'' Dicks said security was already being improved. Dicks said he personally took the committee's findings to Energy Secretary Bill Richardson last fall and urged him to fully implement recommendations from the FBI official now in charge of the department's counterintelligence program. As a result, said Dicks, the Department of Energy now has ``a credible counterintelligence program at our national labs.'' The committee report concludes that an ``insatiable appetite'' for U.S. technology leaves China ready to leap from a 1950s nuclear weapons program to sophisticated designs ``on par with our own.'' A committee Democrat, Rep. John Spratt of South Carolina, questioned whether that conclusion went too far. He said some of the report's findings ``probably would have been left on the cutting-room floor'' if the committee had summoned top intelligence officials. Dicks noted that the Chinese haven't deployed any warheads using the technology that they are alleged to have stolen. He also pointed out that China has about two dozen nuclear weapons compared to the thousands in the U.S. arsenal. The Clinton administration called the committee document a ``good solid report'' but also challenged some its conclusions about the impact of the technology losses on China's nuclear program. ``China is not up to par with the United States on nuclear development. It is far behind us. There is no evidence that that is changing,'' Richardson said in an interview today. The energy secretary said ``the conclusion of wholesale loss'' is not supported. Asked about the report at a Justice Department awards ceremony, Attorney General Janet Reno said, ``I think it presents constructive proposals for how to deal with espionage over the last several decades.'' Two U.S. satellite manufacturers, Loral Corp. and Hughes Electronics, provided China with valuable information to improve the reliability of missiles used to launch communications satellites. That same know-how passed on by the U.S. companies could be used to make China's nuclear missiles more reliable, the report concluded. ``Loral and Hughes showed the PRC (People's Republic of China)how to improve the design and reliability of the guidance system used in the PRC's newest Long March rocket,'' the report said. It said these activities went beyond the license authority given the companies. The report said the espionage dated back to the 1970s and singled out as particularly damaging the loss of design material for one of America's most sophisticated warheads in the 1980s. Richardson said he has taken ``very dramatic steps'' to guard against theft of secrets by tightening computer security at weapons labs and that the report does not reflect counterintelligence and security improvements made this year. At the White House, press secretary Joe Lockhart said Clinton received a classified version of the report Jan. 4. He said the administration doesn't agree with all of the report's analysis but ``found most of the recommendations constructive, and we are in the process of implementing them.'' The report describes a breadth of Chinese espionage that is so threatening to U.S. interests that some members of Congress have compared it to the theft of atomic bomb secrets by the Soviet Union in the 1940s. The fallout could have a profound impact on the operation of U.S. weapons labs and on U.S.-Chinese relations. ``These thefts of nuclear secrets from our national weapons laboratories enabled ... (China) to design, develop and successfully test modern strategic weapons sooner than would otherwise have been possible,'' the report says. With the help of stolen secrets and other technology gains, China ``has leaped, in a handful of years, from 1950s-era strategic nuclear capabilities to the more modern thermonuclear weapons designs'' that took the United States decades to achieve, says the report. China has all along denied conducting any espionage against the United States. China Foreign Ministry spokesman Zhu Bangzao said in Beijing that the allegations were cooked up by people who want to slander China and declared that ``their despicable attempt is doomed to failure.'' The bipartisan committee began investigating technology transfers to China nearly a year ago. Last fall it refocused much of its attention to espionage at U.S. weapons labs. The committee and Clinton administration have been negotiating for several months on how much of the document to make public. The committee of five Republicans and four Democrats found that the primary focus of Chinese espionage was the weapons research labs of Los Alamos and Sandia in New Mexico and Lawrence Livermore in California. Information on a total of seven U.S. warheads, including two of America's most modern, is believed to have been obtained through Chinese espionage in the 1980s, although the losses were not discovered until the mid-1990s. The report also referred to the apparent theft of neutron bomb technology in 1995, but said details remained classified because the matter is under investigation. The report said that in the late 1990s, China obtained ``electromagnetic weapons technology'' that could be used to attack satellites and missiles, improved detection techniques that could be used against submarines, and ``research technology that if taken to successful conclusion could be used to attack U.S. satellites and submarines.'' About a third of the report remains classified, including some details about the espionage investigation at the Los Alamos lab in New Mexico where a scientist was fired in March after being under suspicion of espionage for more than three years. He hasn't been charged. -=-=- 