Nato_s site has been the victim of cyber warfare.

The Web site belonging to the North Atlantic alliance, which is an important source of information during the air strikes on Serbia, has been hit by what officials have described as "hacker-type computer experts in Belgrade". The Web site was down on Wednesday and Nato spokesman J. Shea said it had come under "ping bombardment": the hackers have sent Nato_s computers thousands of empty data packages over the Internet, effectively blocking access to other users. The sabotage is also known as a Denial of Service attack - firing at will at a Web site_s computer servers in order to overload them and make the site crash. Nato was also receiving more than 2,000 e-mails a day from a Belgrade computer, freezing the organisation_s e-mail capacities, and slowing down its systems. Another booby trap that the hackers have reportedly used is macro-viruses similar to the Melissa virus discovered on Friday, and rapidly replicated around the Internet. Users have experienced problems similar to those described by Nato officials at Belgrade_s B92 radio Website. These were cured by deleting all temporary internet files, but the incident was swiftly followed up by the arrival of a mysterious e-mail containing a virus from "Ali".