The modern form of suicide terrorismin which an attacker kills others and himself or herself at the same time by, for example, detonating a car bomb or a suicide vest was unheard of before the 1980s.
A turning point came in 1983, when the Shiite Muslim group Hezbollah exploded a truck bomb at the U.S. marine barracks in Beirut, Lebanon. The blast killed 241 soldiers, and a nearly simultaneous attack on the French military barracks killed 58 soldiers.
Those attacks and a string of others that followed compelled the United States, France, and Israel to withdraw their forces from territory that the suicide attackers viewed as their homeland.
"It sent a message to terrorist leaders around the world that suicide terrorism pays," Pape said.
One organization that picked up on that message was the Tamil Tigers. With 76 suicide attacks to its name, the Sri Lankan rebel group led the world in suicide assaults from 1980 to 2003, according to a database compiled by Pape. The database counted 315 total suicide attacks worldwide in the same period.
"What over 95 percent of suicide attacks have in common is a specific strategic goal to compel modern democracies to withdraw military forces from a territory the terrorists view as their homeland or prize greatly," Pape said.
That motivation is driving many Palestinian suicide bombers to launch attacks against Israeli targets. It may also fuel the increasing barrage of suicide attacks against U.S. targets in Iraq.
But some experts say the motivation behind recent suicide attacks in western Europe by Islamic extremists associated with the al Qaeda network is far murkier. No single strategy or political logic may drive such suicide attacks.
"Suicide attacks were perhaps once mainly organized campaigns aimed at ending perceived occupation of the attackers' homeland," said Atran, the research director at the National Center for Scientific Research in Paris.
"But [they] are now mostly religiously motivated actions by small, loosely connected groups to exorcise cultural humiliation, of which military occupation may be just one manifestation," he added.
Atran has spent years interviewing potential suicide bombers. He debunks the myth of the suicide bomber as a destitute criminal who "hates freedom." Instead, he says, many suicide bombers are educated and maintain strong social networks.
Many potential suicide bombers live in immigrant communities in the West, often marginalized from the host society.
"Today small suicide cells can pop up everywhere, even in Western cities," Atran said. "Seeking a sense of community and a deeper meaning in life, small groups of friends and family from the same area back home bond as they surf Isalmist Web sites to find direction from al Qaeda inspiration, with some veteran jihadi perhaps triggering the group into action."
Free E-Mail News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
SOURCES AND RELATED WEB SITES