Ehud Tenebaum, who calls himself "the Analyzer," and two accomplices, all aged 18, told police they did not penetrate the systems for personal gain. The US Justice Department says the arrest is the culmination of several weeks of investigations into a series of computer intrusions into US military systems.
The Pentagon says the intrusions were apparently aimed at systems that contained unclassified personnel and payroll records. But a spokesman said the Israeli hacker's work was the most organised and systematic attack the Pentagon has seen.
Janet Reno, the US Attorney general said: "We will work around the world and in the depths of cyberspace to investigate and prosecute those who attack computer networks."
In Israel, Linda Menuhin, the police spokeswoman, said no charges had been brought against three suspects being questioned. Mr Tenebaum was later identified by the US Justice Department as the leader of the group. After holding the teenagers at a police station in Bat Yam, a southern suburb of Tel Aviv, police confiscated their passports and forbade any contact between them.
In an interview with the Internet magazine AntiOnline, before he was caught, the Analyzer said the computer penetrations were innocent but added that he had concentrated on US government sites "because I hate organisations". He said: "Chaos, I think it is a nice idea." He also claimed to know the way into some 400 US Defense Department computer systems.
Two other teenagers, arrested in California, were allegedly tutored by the Analyzer.
The first report of a computer break-in came on 3 February from the Massachusetts Institute of Technology's plasma energy laboratory. Penetrations were then reported at a series of military locations, including Nasa.
Benjamin Netanyahu, the Israeli Prime Minister, when asked what he thought of Ehud Tenebaum, said: "Damn good." But he quickly added: "Very dangerous, too."
t BOSTON (AP) - Federal prosecutors have charged a teenager with shutting down an airport communications system.
The Department of Justice said the unnamed boy, from Massachusetts, has agreed to plead guilty. He broke into a Bell Atlantic computer system on 10 March last year, stalling communication between the control tower and aircraft at Worcester Airport for six hours. Power was lost at the control tower and 600 nearby houses were without their telephone service.