The cyber attack is the most intense since Israel's government launched its Internet sites several years ago. It opens a new front in Israel's confrontation with the Arab world. Palestinian rioters have been clashing with Israeli forces for almost a month. At a weekend summit, Islamic countries condemned Israel and called for cutting relations with the Jewish state.
Both sides are emphasizing the public relations aspect of their conflict. Interest in the Israeli government websites has increased noticeably since the riots began Sept. 28, officials said. The targeted sites provide information about the conflict from an official Israeli point of view.
The first shot in the cyberwar was apparently fired by some Israeli teenagers, who bragged to a local newspaper last week that they had succeeded in sabotaging a website of the Hezbollah guerrillas in Lebanon.
Return fire was not long in coming. Uri Noy, who oversees the Foreign Ministry web site, said that several extremist Islamic websites called on their users to attack Israeli sites, providing them access to computer programs that allow users to flood sites with huge amounts of electronic mail, jamming them.
First to feel the effects was the official site of the Israeli Prime Minister's office. After that site was restored, the Foreign Ministry's website was overwhelmed by incoming mail and knocked off the web. Almost two days after the attack began, the site had still not been restored.
The Israeli army repaired its information website, and to increase security, switched from a local server to one connected to the U.S. communications giant AT&T, the military said.
The website of the Knesset, Israel's parliament, was the target of a different king of cyber attack. Hackers broke into the site and tampered with its files, Knesset spokesman Giora Pordes said. He said the attack may have come from Saudi Arabia.
"You cannot be perfectly safe. Any system can be infiltrated," Miki Buzaglo, an Israeli who took credit for first sabotaging the Hezbollah site, said on Israel TV. "There is a war of brains going on here."
An Israeli Internet service provider which hosted the three targeted sites scrambled to make repairs Thursday.
Israeli officials said no damage was done to sensitive computer systems used by the army and the government, since they are insulated from the Internet.
Noy denounced the attacks. "We see the sabotaging of our website as equivalent to the burning of books," he said. He said the bombardment of the site continued even as efforts were made to restore it.
"It's too bad that the Internet has become another battleground," said member of parliament Michael Eitan, the Knesset Internet expert. "We need to have a cease-fire on the web."