The Chinese government announced today that it long ago mastered the technology for building a neutron bomb, emphasizing that Chinese scientists developed the weapon on their own, not through the theft of U.S. nuclear secrets, as has been alleged.

The announcement comes about six weeks after the release of a report written by Rep. Christopher Cox (R-Calif.) that said China has stolen many secrets from U.S. nuclear laboratories over the last 20 years -- including information on the neutron bomb.

China made its proclamation in a report titled "Facts Speak Louder Than Words, and Lies Will Collapse by Themselves -- Further Refutation of the Cox Report." The report, which was released by the Information Office of the State Council, China's cabinet, did not say whether China has in fact conducted tests, begun mass production or deployed the weapon. The Cox report said China tested a neutron bomb in 1988, but China has never confirmed that.

"The neutron bomb seems quite mysterious to ordinary people. In fact, it is a kind of hydrogen bomb," the Chinese report said. "Since China has already possessed atom bomb and H-bomb technologies, it is quite logical and natural for it to master the neutron bomb technology through its own efforts over a reasonable period of time."

Neutron bombs are designed to kill humans with a lethal burst of neutrons but to leave buildings intact. They leave little radioactive fallout.

Today's announcement was a departure from usual Chinese government practice over the last several decades of releasing almost no information about its nuclear program. It was unclear why the government would release such information voluntarily now, but it did say the announcement was designed to counter the "groundless, vicious slander" against China and its scientists made in the Cox report.

Weeks before today's announcement, China made a thorough attack on the Cox report weeks ago, leading to speculation today's move could be designed to send a broader message about China's own power. The announcement comes amid heated new tensions with Taiwan and in the wake of the U.S. bombing of the Chinese embassy in Belgrade during the NATO campaign in Yugoslavia. The Chinese government continues to assert the attack was intentional, despite the U.S. explanation that it was a mistake.

David Shambaugh, an expert on Chinese security policy at George Washington University, called today's announcement "strange" and said he "wouldn't link it necessarily" to either the Taiwan crisis or the embassy bombing. "We knew they had it, now they've confirmed it. That was just one of the allegations in the Cox report, and not one of the more worrying ones. It's 20-year-old technology."

The Cox report concluded that China is preparing to target Taiwan with neutron warheads, but that idea was rejected by the larger U.S. intelligence community, which expressed doubt that the Chinese would ever use a nuclear weapon on what they consider their own territory.