Or so suggests a new study:

Robert Pape, a University of Chicago political science professor and former Air Force lecturer, will present findings on Capitol Hill on Tuesday that argue that the majority of suicide terrorism around the world since 1980 has had a common cause: military occupation.

Pape and his team of researchers draw on data produced by a six-year study of suicide terrorist attacks around the world that was partially funded by the Defense Department's Defense Threat Reduction Agency. They have compiled the terrorism statistics in a publicly available database comprising some 10,000 records on some 2,200 suicide terrorism attacks, dating back to the first suicide terrorism attack of modern times the 1983 truck bombing of the U.S. Marine barracks in Beirut, Lebanon, which killed 241 U.S. Marines.

"We have lots of evidence now that when you put the foreign military presence in, it triggers suicide terrorism campaigns, ... and that when the foreign forces leave, it takes away almost 100 percent of the terrorist campaign," Pape said in an interview last week on his findings.