SAM TANENHAUS; Sam Tanenhaus, a Vanity Fair contributing editor, is author of "Whittaker Chambers."
AS the war in Iraq began last week, some prominent members of the Bush administration were repeating their hope that the removal of Saddam Hussein will be the catalyst for a wave of democratic reform throughout the Middle East. In making their case these planners have revived a staple of cold-war thinking, the domino theory: the idea that sudden change in the leadership of one nation can set off a chain reaction in its neighbors, transforming an entire region.
In its original formulation, the domino theory was invoked fearfully. At the time, the most active agent of wholesale change was thought to be Soviet Communism. America's job was to keep the dominoes from falling, all over the globe. But in today's unipolar world, a so-called positive or reverse domino theory has emerged. It envisions democracy as the great insurgent movement of our time, with the United States leading the revolution.
Either way, the image of nations as falling dominoes, each toppling into the next, has proved remarkably durable, shaping the policies of presidents from Dwight D. Eisenhower on.
Eisenhower, who was not generally known for his vivid formulations, introduced the concept, shortly after French forces were overwhelmed by Communist guerrillas in Dien Bien Phu, a valley in Vietnam, in 1954. Asked at a press conference to explain the significance of this distant conflict, Eisenhower said that one Communist victory in the region could set off a "possible sequence of events," including "the loss of Indochina, of Burma, of Thailand" and perhaps Indonesia as well.
All this "might follow from what you might call 'the falling domino' principle," he said. "You had a row of dominoes set up, and you knocked over the first one, and what would happen to the last one was the certainty that it would go over very quickly. So you could have a beginning of a disintegration that would have the most profound influences."
The idea made sense to many who had strong memories of the calamitous prelude to World War II. The Western powers had stood by as Hitler annexed Austria and grabbed Czechoslovakia, putting him into position to invade Poland and pursue further conquests. Eisenhower drew this parallel in an exchange with Winston Churchill, citing the failure of the great democratic powers "to halt Hirohito, Mussolini and Hitler" when they had the opportunity.
John F. Kennedy, Eisenhower's successor, reportedly expressed skepticism about the theory's logic in the first year of his presidency, partly because it reduced the complex tangle of regional forces to a single tug of war between Washington and Moscow.
BUT Kennedy knew that the formula had already taken root in Southeast Asia. As the historian Arthur M. Schlesinger Jr., a Kennedy adviser, later observed, "Whether the domino theory was valid in 1954, it had acquired validity seven years later, after neighboring governments had staked their own security on the ability of the United States to live up to its pledges to Saigon."
Faced with a crisis in Laos two months into his presidency, Kennedy, echoing Eisenhower, warned that "the security of all Southeast Asia will be endangered if Laos loses its neutral independence."
But Indochina proved a troubling test case once the United States became mired
in Vietnam. In 1966, an early critic of the war, Sen. J. William Fulbright,
pointed out that the domino theory obliged the United States to "fight
in one country to avoid having to fight in another, although we could with
equal logic have inferred that it is useless to fight in one country when the
same conditions of conflict are present in another."
Worse, as the war dragged on, policies meant to prop up wobbly dominoes instead
had the effect of shoving them in the opposite direction. South Vietnam grew
so dependent on American support that when aid was cut off in 1975 it was unable
to ward off the invading North. President Richard M. Nixon's secret bombing
of Cambodia destabilized that country, clearing the way for the Khmer Rouge
under its brutal dictator, Pol Pot, to take charge.
When the fall of Saigon failed to initiate a regionwide Communist insurgency, the domino theory looked discredited for good. Still, it continued to influence foreign policy, particularly in Latin America and the Caribbean. Unable to dislodge Fidel Castro in Cuba, the United States intervened repeatedly in nearby conflicts -- in Chile, Nicaragua, El Salvador and Grenada -- in the belief that every additional foothold gained by Communists increased the threat in the hemisphere.
Today, the domino theory is so ingrained in American foreign policy that it is often the subject of sophisticated analysis. The Yale historian John Lewis Gaddis has written about the "psychological domino effect" that causes smaller nations to align themselves with great powers. In his revisionist history, "Vietnam: The Necessary War," Michael Lind identified three versions of the domino theory: "a regional domino effect, a global revolutionary wave effect or a global bandwagon effect."
THE haunting memory of the old theory and its failings is still with us today, even as the image of falling dominoes is being reformulated in the optimistic vision embraced by Paul D. Wolfowitz, the deputy defense secretary, and others who suggest that the war in Iraq might be the first step toward establishing democracy in the Middle East.
In a recent appearance on Capitol Hill, George J. Tenet, the director of central intelligence, cautioned against making the Iraq war the basis of "a big domino theory about what happens in the rest of the Arab world."
And shortly before President Bush flew to the Azores a week ago, The Los Angeles Times reported that a classified State Department document, presented to top government officials, made a strong case that the fall of Mr. Hussein is unlikely to unleash democratic change in the region. The report was pointedly titled, "Iraq, the Middle East and Change: No Dominoes."