May 20, 2002 -- FBI Director Robert Mueller today warned that suicide bomb attacks in the United States are "inevitable," and sources told ABCNEWS al Qaeda and other terror groups have met to discuss joining forces against America and the West.
Leaders of al Qaeda, Osama bin Laden's terror network, met in a summit with leaders of two Middle Eastern militant groups, Hamas and Hezbollah, as well as a number of other groups linked to terrorism in late March, U.S. intelligence and law enforcement officials told ABCNEWS.
Hamas has claimed responsibility for many of the suicide bomb attacks against Israel. Lebanon-based Hezbollah led a guerrilla war against Israel's occupation of territory in southern Lebanon, and is blamed for the 1983 bombing of the U.S. Embassy in Beirut, Lebanon, that killed 241 American servicemen.
At the Lebanon meeting, the three groups discussed tactics and the possibility of an unprecedented level of joint activity, U.S. officials said, including a possible new round of attacks against America, Great Britain, and other targets.
The March secret summit means bin Laden's group and the others put aside rivalries to work together, officials said.
"It suggests a new departure which is very startling and dangerous because they have not worked together before," said Vince Cannistraro, an ABCNEWS expert and former CIA counterterrorism chief.
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Suicide Bombings in the U.S. 'Inevitable'
Mueller, the FBI director, said today he expected terrorists to mount "walk-in" suicide bombing attacks in the United States, in which militants would strap explosives to themselves and detonate them in public spaces.
"I think we will see that in the future; I think it's inevitable," Mueller said in response to a question during a speech to a meeting of the National Association of District Attorneys in suburban Alexandria, Va.
"I wish I could be more optimistic," he said.
Mueller's warning came as U.S. intelligence officials said they believe al Qaeda has reconstituted itself and is ready to attack the United States again. Authorities admit little knowledge of when or how al Qaeda may strike, however.
"It could happen tomorrow, it could happen next week, it could happen next year," Vice President Dick Cheney said Sunday on Fox News, adding that another large-sale terrorist attack on the United States is "almost a certainty."
Officials said they have picked up a flood of new terror threats from interceptions of electronic communications between members of bin Laden's terror network around the world. The level of "chatter" is as high now as it was in the months before the terror attacks on the World Trade Center and Pentagon, officials said.
"They definitely have the will; they've shown that," said Marine Corps Lt. Gen. Gregory Newbold.
"They have the numbers of people who operated out of training camps in Afghanistan for a number of years. They have the resources, so I think it's predictable," he said.
An al Qaeda official claimed responsibility over the weekend for the bombing of an historic synagogue in Tunisia last month that killed 19, including German tourists.
U.S. officials have also warned that other Islamic extremist groups such as Hezbollah and Egypt's Islamic Jihad could be planning attack in the United States.
Warnings on Apartment Buildings
The threats led the FBI to issue a warning last week that terrorists may simply rent an apartment in a skyscraper and pack it with explosives to bring down the building. Some building managers responded by posting warnings in the lobby and informing tenants.
"They told us to be vigilant and aware of the possibility of someone renting out apartments to possibly blow up something," said Donald Daniel, resident of one such building in San Francisco.
The new warning is based on overseas intercepts and interviews with Abu Zubaydah, a captured bin Laden lieutenant, sources told ABCNEWS. They admitted officials are unsure if the threat is credible.
The warning is similar in nature to past warnings regarding shopping malls and other gathering places, the sources say, and was issued out of an abundance of caution.
ABCNEWS chief investigative correspondent Brian Ross and Pierre Thomas in Washington contributed to this report.