Chinese and American computer hackers were engaged in an all-out cyber war Tuesday, with U.S. hackers launching a counter-attack to Monday's massive Chinese defacement of U.S. Web sites.

Calling their effort "Project China: Asia Domination," U.S. hackers have been organizing to deface Chinese Web sites, according to the Internet security firm Vigilinx, which has been closely monitoring the activity.

Right now, the Chinese hackers appear to be winning the war, having defaced 76 American Web sites late Tuesday morning to the American hackers, who have hit 63 Chinese sites, Vigilinx said.

But the tables could soon change. Jerry Freese, director of intelligence at Vigilinx, said the American hackers have mostly been individuals going up against a highly organized Chinese hacking initiative. But now, the U.S. hackers are officially organizing.

In a mostly obscene message directed at the Chinese hackers, a Web site defaced by American hackers reads in part, "Get ready to meet a strike force with strength the world has never seen before! We are going for all out cyber warfare on your .gov.cn boxes and every other box that you ... haven't secured! Hold onto your boots because many will fall to the wrath of the blood bath!"

Freese said Vigilinx had not verified that the message represented a hacking coalition, but he said the information his firm was compiling indicated the American hackers were organizing.

The Chinese-American hacker war picked up Monday when Chinese computer hackers launched a massive attack against U.S. Web sites, including those of United Press International, the U.S. Department of Labor and the Navy's communication center.

The attacks were aimed at the U.S. in retaliation for the April 1 collision between a U.S. Navy surveillance plane and a Chinese fighter jet, which the Chinese say was caused by the Americans.

By Tuesday, American hackers were targeting Chinese government sites, as well as the Web sites for a Chinese university and what appeared to be a non-profit organization. While both sides appear to be targeting sites randomly, Reese said the hackers were choosing sites based not on content or ownership as much as their ability to breach the technology.

So far, neither side has inflicted much damage, opting to "deface" the Web pages of sites rather than attack the servers or launch viruses or malicious code. For example, on the UPI's site, Chinese hackers replaced the site's home page with the image of a waving Chinese national flag and anti-American slogans scrawled in a mix of Chinese characters and English letters.

The copy that appeared in English read, "The Great Chinese Nation Hooray! USA Will Be With Responsibility for the Accident Totally!!! Protest USA sell Weapon to Taiwan, Break The World Peace!!! USA IS BITCH! I am from China---Peak."

Peak is the Internet name of one of the hackers.

"This becomes a game," said Mike Assante, vice president of intelligence at Vigilinx, pointing out that confirming the origin of the hacking conclusively would require forensic analysis of the sites. In most cases, he said, system administrators can easily repair the damage.

A more ominous element of the attacks is that hacking is a capital offense in China. Two hackers who broke into a Chinese bank computer network and stole $31,400 were sentenced to death in 1998. While security experts don't think the Chinese government is sponsoring the attacks, they believe Beijing would have to be condoning an effort this large and organized.

Meanwhile, hacker-tracking groups, such as Attrition.org, claim the hacking has been going on for some time, with individual attacks pre-dating the surveillance plane collision, and did not take on political overtones until the media picked up the story.

A group known as the "Honkers" Union of China claimed responsibility for some of the attacks Monday, displaying their name on the home page of the sites they infiltrated below several lines of anti-American slogans. The group replaced the home page of each site with one reading "The People's Republic of China is Everlasting. Down With USA. Down With Yankees."

On the Web site 777.wireless.com, the group posted pictures of the Chinese military and a tribute to Wang Wei, the Chinese pilot who died in the collision with the American surveillance plane.

Among other U.S. sites defaced by the Chinese hackers Monday were the site for the California Energy Department, the site for a European scuba diving outfit, a California manufacturing firm and a non-profit organization that assists small business owners, as well as a long list of sites for American businesses and organizations.

A partial list of hacked U.S. government sites includes those of the Navy communication station in Washington; the U.S. Mineral Resource Administrative Bureau; the U.S. Department of Labor and the U.S. Department of Health.

Don Eskes, president of Filter Corp., a manufacturing company in Fresno, Calif., told Fox News that he learned his site had been hacked just after opening up Monday from one of the company's East Coast dealers. The site, which Eskes said was maintained by an independent web provider, had been repaired by 11:45 a.m. EST.

Jeff Higginbotham, network administrator for the Central Valley Business Incubator in Clovis, Calif., said his site was hacked through an attack on the outside web hosting company that maintained the advertising and promotion portion of the site. The web-based services the organization provides for its clients are hosted internally and were not affected, he said.

"It's really just a minor inconvenience," Higginbotham told Fox News. The hacked portion of the site was still displaying the Chinese pages at noon, EDT.

The "Red Guest Alliance News" said the cyber-assault would commence at 9 a.m. EDT on April 30 and was planned to continue through the May Day holidays of May 1-7. The organization allegedly mobilized its force by calling a cyberspace rally around 7 a.m. EDT.

The official Xinhua News Agency has made no public comments on the so-called "hacker war," but Chinese chat rooms and unofficial media outlets were buzzing with reports of the planned attack.

While China's official press has not commented on the attack, Chinese cyber-surfers reportedly overwhelmingly support the "51 Hacker War." According to the results of a poll reported by China.com, nearly 85 percent of 2089 respondents firmly support the Chinese "Red Guest" action.

Last week, the National Infrastructure Protection Center issued a warning that Chinese hackers may coordinate an attack against U.S. web sites with May Day festivities Tuesday.