What motivates a suicide terrorist? Is there a transitional moment that creates a terrorist? What are the risk factors that lead to suicide attacks?

In the aftermath of 9/11, University of Chicago political science professor Robert Pape found himself flooded with such questions from a public in search of answers. And the truth was, he wasn't sure.

His response was to compile the first known database of all suicide terrorist attacks recorded worldwide in modern history, sorting and analyzing them by date of attack, targets, weapons utilized and death tolls, then cross referencing that against the geo-politics of foreign occupations.

From that foundational work, Pape would create the Chicago Project on Security and Terrorism (CPOST), which he now directs, and the Suicide Attack Database, a publicly searchable resource that may offer the most complete list available of transnational suicide attacks reported from 1982 through 2015 — more than 4,280 attacks in over 40 countries.

Within that data, Pape began to see patterns.

Instead of poverty and extremist politics — or even Islamist fundamentalism — the primary motivation for suicide terrorists instead appeared to be a desire to force democratic countries to abandon occupation of what terrorists' consider to be their homeland.

"The key risk factor for both secular and religious suicide attacks is military occupation — it's driving 95 percent of the suicide attacks we face," Pape said in a talk hosted by Emory's Halle Institute for Global Learning on March 25 in the Emory Conference Center Hotel.

"The core issue with military occupation is that there is some force keeping a government in power over a body of people that does not support that government," he explained.

"That government is in charge of a body of people, controlling an economic, political and social way of life. The people underneath want to fight to determine their own way of life."

Philip Wainwright, vice provost for global strategy and initiatives and director of the Halle Institute for Global Learning at Emory, said he was pleased to see a robust turnout and high level of interest in Pape's presentation.

"This is a complex issue with global implications, and it deserves thoughtful investigation beyond the news headlines," he said.

The strategy of suicide attacks

Co-hosted by Emory's Department of Middle Eastern and South Asian Studies (MESAS) and the Atlantic Institute, Pape's presentation was titled, "The Strategic Logic of the Islamic State of Iraq and Syria."

During introductions, MESAS Chair Vincent Cornell, Asa Griggs Candler Professor of Middle Eastern and Islamic Studies, said he came to know Pape "partly through my own work" in the theologies of fundamentalism. He credits Pape as being "one of the first major scholars to point out that when it comes to terrorism, a lot of the things we think are important are not necessarily the most important things."

In his talk, Pape challenged theories that the greatest terrorism threat to the U.S. is now driven by Muslim fundamentalists. "Islam has been around for 1,500 years," he said. "Why no suicide attacks before now? They are telling us over and over again — it's because of occupation."

Through his research, Pape found the taproot of suicide terrorism is more likely "an extreme strategy for national liberation," he writes in his book, "Dying to Win: The Strategic Logic of Suicide Terrorism."

According to his data, which includes more than 15,000 online documents in English and native languages, "territory is centrally important to each and every suicide attack."

For example, the Shi'a Islamist militant group Hezbollah didn't exist until Israel invaded southern Lebanon in 1982. "One month later, Hezbollah was born and began to experiment with suicide attacks," Pape said.

When U.S. President Ronald Reagan decided to withdraw American combat forces from Lebanon after a Hezbollah suicide mission led to the deaths of 299 French and American servicemen, it effectively ended Lebanese suicide attacks against Americans, Pape noted.

"The onset (of the attacks) was really caused by the presence of our military troops," he said. "It created the monster that created the suicide attacks. David not only knocked Goliath in the eye, he knocked him out of the game. When we left Lebanon, that ricocheted in terrorist groups around the world."

"I'm afraid that we taught them a lesson — suicide terrorism pays big dividends. We can't undo that lesson," he added.

Military occupation 'not the answer'

Terrorism attacks by al-Qaeda from 1995 to 2004 also fit that pattern, Pape said, with 69 recorded suicide attacks — the majority coming from Saudi Arabia, with "two-thirds from the Arabian Peninsula, where the U.S. was beginning to station combat forces."

According to his data, "if we have more occupation, which we did after 2004, we get more suicide attacks in the key places of our occupations," Pape said. "We try to solve the problem with occupation and we only make it worse."

Subsequent suicide terrorism patterns have "overwhelmingly confirmed the research," he added. "In Afghanistan in 2006 we spread our forces all around the country, and suicide attacks spike accordingly."

After Pape played a terrorism recruitment video featuring American-born Adam Gadahn, who would join al-Qaeda as a media advisor, he told the audience, "There are no promises of 72 virgins — from beginning to end, this is a plea for help for a kindred population facing real atrocities. That's the argument that's winning over people."

In fact, ISIS was "born by our occupation of Iraq," Pape said. "It did not exist before that. The first suicide attacks ever in Iraqi history began a few weeks after our invasion of outposts."

A call for more U.S. ground troops in Iraq is only likely "to make matters much, much worse," he added. "Military occupation is not the answer."

While ISIS does pose "a real, but low-level threat in the U.S.," the greatest danger is likely to come from lone wolf attacks, such as the Boston Marathon bombing, Pape said.

The greater threats from ISIS will come in the Middle East. "Truth be told, the reason we care about the region is oil. No politician will get on TV and tell you that, but if oil wasn't there, we wouldn't be there."

In the end, the best response for the U.S. will be a strategy that relies on off-shore balancing — offering economic support for onshore allies, as opposed to boots on the ground, Pape said.

"I care about saving American lives, and this is the best way to save lives," he said.