WASHINGTON - 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-Qaida or other Middle Eastern terrorist groups but sympathize with their grievances, intelligence and law enforcement officials say.
A classified FBI intelligence bulletin, issued 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-Qaida.
"Lone extremists represent an ongoing terrorist threat in the United States," the FBI wrote in the bulletin. "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 believed the threat of such attacks by individual extremists was growing because of the possibility of a U.S.-led war against Iraq.
The officials said a war would inflame anti-American sentiment throughout the Arab world, adding to a variety of causes that have stoked hatred of the United States. One of the main issues expressed by many Arabs is their belief that the United States has supported Israel in its effort to put down the Palestinian intifada, or uprising. And some people may decide to strike against U.S. targets almost on the spur of the moment, officials warned.
Moreover, analysts regard the new taped message believed to be from Osama bin Laden as a summons to his followers, and perhaps to new sympathizers, to conduct actions against the U.S. targets in response to the possible war in Iraq.
The message believed to be bin Laden's was initially broadcast by al-Jazeera, the Arabic language television station, as were his messages urging broader action against the United States and its allies. Those were followed within days by terrorist strikes against U.S. and other targets abroad.
Counter-terrorism officials have long feared that a solitary terrorist with an automatic weapon or one committed to a suicide bombing could inflict heavy casualties in the United States.
The threat posed by what officials refer to as "lone wolves" who suddenly decide to act because of their increasingly radicalized views toward the United States is a major concern for U.S. officials because their actions are difficult to predict or prevent.
"Many lone extremists have no links to conventional terrorist groups," the bulletin read. "In fact, FBI analysis suggests that psychological abnormalities, as much as devotion to an ideology, drive lone extremists to commit violent acts."
As the CIA and the FBI scramble to try to deal with intelligence suggesting that al-Qaida hopes to launch another attack soon against the United States, the threat posed by individual extremists who may suddenly decide to attack Americans is a wild card facing counterterrorism officials.
FBI Director Robert S. Mueller III noted the threat of lone extremists in testimony early this month to the Senate Intelligence and Armed Services Committees.
"The threat from single individuals sympathetic or affiliated with al-Qaida, acting without external support or surrounding conspiracies, is increasing, in part because of heightened publicity surrounding recent events such as the October 2002 Washington-area sniper attacks and the anthrax letter attacks," Mueller said.
One case mentioned in the FBI bulletin was that of Hesham Mohamed Ali Hadayet, an Egyptian immigrant who fatally shot two people at El Al Airlines' ticket counter at Los Angeles International Airport in July. While there are indications that Hadayet had connections to terrorists, the FBI says it believes he acted alone.
U.S. counter-terrorism officials who have studied the nature of the threat from extremist Islamic terrorist groups said that they now realized that they must distinguish between intricate plots that are carefully coordinated by groups like al-Qaida and the less organized actions of people on the fringes of extremist movements.
The FBI bulletin mentioned other examples of people who had engaged in the kind of violence that has worried counter-terrorism officials. They include Timothy J. McVeigh, who was executed for the 1995 bombing of the federal building in Oklahoma City. McVeigh began plotting the bombing after a Michigan militia group distanced itself from him because "it became apparent that his views were too radical," the bulletin read.
Another solitary extremist identified in the FBI bulletin was Paul J. Hill, an anti-abortion militant who fatally shot an physician and his assistant in Pensacola, Fla., in 1994.
Lone extremists who belong to conventional terrorist groups may commit acts without the prior knowledge of the group's leadership, the bulletin said.
Beyond fears about people loosely affiliated with al-Qaida, counter-terrorism officials have expressed concern that Middle Eastern terror groups such as Hamas and Hezbollah could signal their followers to conduct independent terrorist actions in the event of a U.S.-led invasion of Iraq, a senior government official said.
In his Senate testimony on Feb. 11 and 12, Mueller said that Hamas and Hezbollah had the resources in the United States to launch terrorist attacks, but added that neither group "appears to have sufficient incentive to abandon their current fund-raising and recruitment activities in the U.S. in favor of violence."
But Mueller warned that each group could "in short order develop the capability to launch attacks should international developments or other circumstances prompt them to undertake such actions."
Federal authorities have intensified their efforts to keep track of these groups in the United States, along with people associated with them, particularly those on the periphery who are believed to be capable of violence.