The 17-year-old boy, who went by the pseudonym "DKD," hacked into sites and often replaced their welcome pages with political slogans, said Eric Voulleminot of the Regional Service of Judicial Police in Lille.
The teenager, who was not identified by police, often wrote messages in favor of the Palestinians or against U.S. military policy and is accused of attacking sites in France, Britain, Australia and the United States, Voulleminot said.
The attacks on American sites occurred mostly during the U.S.-led invasion of Iraq, he said. The boy allegedly concentrated on government office and military sites, including that of the U.S. Navy.
Suspected of attacks over 14 months, he was arrested June 24 at his parents' home outside of Paris and released under surveillance. But he is being investigated in Lille, 125 miles north of Paris, where officials accuse him of hacking into the Pas-de-Calais prefectural Web site.
Investigators think his goal was showing off technical skill rather than spreading a political message.
"It's difficult to gauge his level of political militancy," Voulleminot said. "This young man, who operated alone, did not belong to any political group."
The probe was launched in April after the prefectural office's page was damaged. Anti-hacker specialists in Lille worked with U.S. investigators who "were worried about the boy's work," Voulleminot said.
The suspect faces a maximum sentence of three years in prison and a fine $50,850.