Three general patterns in the data support these conclusions. First, nearly all suicide terrorist attacks -- 301 of the 315 in the period I studied -- took place as part of organized political or military campaigns. Second, democracies are uniquely vulnerable to suicide terrorists; America, France, India, Israel, Russia, Sri Lanka and Turkey have been the targets of almost every suicide attack of the past two decades. Third, suicide terrorist campaigns are directed toward a strategic objective: from Lebanon to Israel to Sri Lanka to Kashmir to Chechnya, the sponsors of every campaign -- 18 organizations in all -- are seeking to establish or maintain political self-determination.

Before Israel's invasion of Lebanon in 1982, there was no Hezbollah suicide terrorist campaign against Israel; indeed, Hezbollah came into existence only after this event. Before the Sri Lankan military began moving into the Tamil homelands of the island in 1987, the Tamil Tigers did not use suicide attacks. Before the huge increase in Jewish settlers on the West Bank in the 1980's, Palestinian groups did not use suicide terrorism.

And, true to form, there had never been a documented suicide attack in Iraq until after the American invasion in 2003. Much is made of the fact that we aren't sure who the Iraqi suicide attackers are. This is not unusual in the early years of a suicide terrorist campaign. Hezbollah published most of the biographies and last testaments of its "martyrs" only after it abandoned the suicide-attack strategy in 1986, a pattern adopted by the Tamil Tigers as well.

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At the moment, our best information indicates that the attackers in Iraq are Sunni Iraqis and foreign fighters, principally from Saudi Arabia. If so, this would mean that the two main sources of suicide terrorists in Iraq are from the Arab countries deemed most vulnerable to transformation by the presence of American combat troops. This is fully consistent with what we now know about the strategic logic of suicide terrorism.

Some have wondered if the rise of suicide terrorism in Iraq is really such a bad thing for American security. Is it not better to have these killers far away in Iraq rather than here in the United States? Alas, history shows otherwise. The presence of tens of thousands of American combat forces on the Arabian Peninsula after 1990 enabled Al Qaeda to recruit suicide terrorists, who in turn attacked Americans in the region (the African embassy bombings in 1998 and the attack on the destroyer Cole in 2000). The presence of nearly 150,000 American combat troops in Iraq since 2003 can only give suicide terrorism a boost, and the longer this suicide terrorist campaign continues the greater the risk of new attacks in the United States.

Understanding that suicide terrorism is mainly a response to foreign occupation rather than a product of Islamic fundamentalism has important implications for how the United States and its allies should conduct the war on terrorism. Spreading democracy across the Persian Gulf is not likely to be a panacea so long as foreign combat troops remain on the Arabian Peninsula. If not for the world's interest in Persian Gulf oil, the obvious solution might well be simply to abandon the region altogether. Isolationism, however, is not possible; America needs a new strategy that pursues our vital interest in oil but does not stimulate the rise of a new generation of suicide terrorists.

BEYOND recognizing the limits of military action and stepping up domestic security efforts, Americans would do well to recall the virtues of our traditional policy of "offshore balancing" in the Persian Gulf. During the 1970's and 1980's, the United States managed its interests there without stationing any combat soldiers on the ground, but keeping our forces close enough -- either on ships or in bases near the region -- to deploy in huge numbers if an emergency. This worked splendidly to defeat Iraq's aggression against Kuwait in 1990.

THE Bush administration rightly intends to start turning over the responsibility for Iraq's security to the new government and systematically withdrawing American troops. But large numbers of these soldiers should not simply be sent to Iraq's neighbors, where they will continue to enrage many in the Arab world. Keeping the peace from a discreet distance seems a better way to secure our interests in the world's key oil-producing region without provoking more terrorism.

Op-Ed Contributor Robert A. Pape, an associate professor of political science at the University of Chicago, is the author of the forthcoming "Dying to Win: The Strategic Logic of Suicide Terrorism."