The alleged plan to attack Fort Dix in New Jersey is the latest in the line, and it reveals much about the challenges, and the advantages, of dealing with homegrown radicals with no direct connection to al-Qaida.
Experts say homegrown groups can be small and difficult to uncover, but they often make breathtakingly foolish mistakes, and lack funding, discipline and training.
The Fort Dix suspects were a seemingly clumsy and dithering group of young Muslim men who turned out to be their own worst enemy. They allegedly sent a jihadi videotape to a local store to be copied, prompting the clerk to tip off authorities. The FBI infiltrated the group and watched them for more than a year before moving in this week.
The purported plotters allegedly held weapons training sessions and had scoped out their target, but they also at times seemed like reluctant warriors. They asked the FBI informant if he could lead the operation because he had more experience, then said they shouldn't carry out the attack without a fatwa - a religious edict - from a Muslim cleric.
One of the men even reportedly expressed misgivings about using automatic weapons for what would have been a bloody rampage against soldiers at the Army post, noting that such weapons are illegal.
"There are a lot of different violent desires, and a lot of different fantasies out there, but most of them are not going to materialize because the moment these relatively unsophisticated people act on them, they are going to get caught," said Magnus Ranstorp, a terrorism expert at the Swedish National Defense College. "It takes a lot of technical skills to pull something like this off in today's security environment."
Still, a lack of al-Qaida training - and even a bit of bungling - does not always mean failure. Ranstorp and other analysts say the threat from little-known homegrown terror cells is still the most significant facing the world today.
The March 11, 2004, bombing onslaught against commuter trains in Madrid, Spain, which killed 191 people, was allegedly carried out by Muslim immigrants with long rap sheets for drug trafficking and other petty crimes, but no connection to Osama bin Laden.
And the July 7, 2005, bombings in London, which killed 52 people and the four bombers, were undertaken by British Muslims radicalized at home. In that case, however, authorities are suspicious of trips the suspects made to Pakistan before the attack and believe the men might have received al-Qaida instructions.
"From the evidence we have from the United Kingdom, it seems what appear to be spontaneous and amateur networks are far from so," said Anthony Glees, a terrorism expert who is director of the Brunel Centre for Intelligence and Security Studies in London. "What we know is, at a critical moment somebody experienced will be wheeled on to instruct terrorists on how to make a bomb explode." Such a person has not been identified in the Fort Dix plot, and U.S. authorities say they know of no connection between the arrested men and international terrorist groups. In an atmosphere of fear like that in the U.S. and parts of Europe, it is sometimes hard to separate the significant threat from the pipe dream. In a large number of headline-grabbing plots, particularly in America, homegrown terrorists seem to have been long on cataclysmic imagination and short on ability to carry out their plans. Newspapers screamed with fire and brimstone when arrests were made in an alleged plot to flood lower Manhattan by blowing up underwater commuter tunnels, but the scheme was later revealed to be little more than a fantasy. Canadian officials shook up their countrymen last June by announcing they had broken up a homegrown terror scheme in which 17 males were plotting to bomb buildings. A defense lawyer added to the sensation by saying the suspects were also accused of planning to break into Parliament and behead the prime minister and other officials. The Sears Tower plan was barely in its infancy when the alleged plotters were arrested. And Jose Padilla, who the government originally accused of seeking to set off a radioactive "dirty bomb" in a U.S. city, was not close to getting his hands on such a weapon. The charge is no longer part of the case against him. Still, the Madrid train attack shows that even unaffiliated terrorists can make a series of blunders but unleash carnage if authorities are caught off guard. In the weeks before the attack, police stopped a car carrying several of the eventual bombers on a highway leading to Madrid, but they didn't find the explosives hidden inside. Authorities even had one of the ringleaders under surveillance in a drug inquiry, but failed to realize his taped conversations were about a terror plot. An attempted terror attack last July 31 in Cologne, Germany, saw two suspects smuggle bombs made of barbecue gas canisters with alarm-clock trigger mechanisms onto two trains in suitcases. The head of Germany's Federal Crime Office, Joerg Ziercke, said plans for constructing the bombs were found on the Internet, but the plotters diverged slightly from the blueprint, so when the detonators went off they didn't fire the bombs. Crucial clues - like DNA evidence and fingerprints - were left behind because the two were counting on the bombs obliterating all the evidence. They were also caught on surveillance tapes planting the bombs and traveled on their own passports. One was arrested in Lebanon, the other in Germany before he could flee. "In general the train bombers didn't seem to be very well skilled in technical things, but they were skilled enough to construct those bombs that might have functioned," said Manfred Murck, deputy head of the state agency that tracks extremism in Hamburg, Germany. "They are not experts but it's not too difficult to learn how to construct a bomb if you have some time and some logic." (AP) AP writers David Rising in Berlin, D'Arcy Doran in London and Elaine Ganley in Paris contributed to this report. AP-CS-05-09-07 1437EDT