The possibility of war with Iraq could unleash acts of anti-American violence in the United States or overseas by individual extremists who do not belong to Al Qaeda or other Middle Eastern terrorist groups but sympathize with their grievances, intelligence and law enforcement officials say. A classified F.B.I. intelligence bulletin, issued on Wednesday to state and local law enforcement agencies throughout the country, warned the authorities to be on the alert for lone terrorists who are not directed by organizations like Al Qaeda. “Lone extremists represent an ongoing terrorist threat in the United States,” the bulletin said. “Lone extremists may operate independently or on the fringes of established extremist groups, either alone or with one or two accomplices.” Law enforcement and intelligence officials said in interviews in recent days that they believe the threat of such attacks by individual extremists is growing because of the possibility of an American-led war against Iraq. Full Story