SEPT. 19, 1994, 20,000 troops landed in Haiti in a multinational force backed by the United Nations and led by the United States. Their mission was to end the reign of terror of Haiti’s brutal military regime and pave the way for the return of the country’s first democratically elected president, Jean-Bertrand Aristide.

Aristide had been forced into exile in a bloody 1991 coup after challenging the country’s military and economic elite, giving hope to millions of impoverished Haitians who at last felt they had a voice in shaping their own destiny. A month after entering Haiti, US troops had helped stabilize the country without casualties, the military regime had been chased out, and Aristide was back in office. Mission accomplished.

The story, of course, does not end that way. In March 2004, US Marines are once again in the streets of Port-au-Prince, and Haitians once again face the very dangers that confronted them a decade ago. Their cities have been overrun by armed gangs led by convicted criminals; their president has once again been pressured to flee; all semblance of law and government authority has collapsed; and Haiti remains the poorest country in the Western Hemisphere.

What went wrong, and who’s responsible? There’s plenty of blame to go around, from Aristide himself to his political opponents to the international community. But in the end, it was a combination of action and inaction by the Bush administration that delivered the final blow last week to Haiti’s struggling democracy as the country plunged into a state of anarchy.

To understand what happened, it’s necessary to look back to the early days of the Aristide presidency. Aristide’s internationally supervised election in 1990 signaled a chance to break the cycles of repressive and rapacious leadership that had plagued Haiti for most of its two centuries of independence. Having led the movement to rid his country of the three-decade dictatorship of the Duvaliers, Aristide rode to power on the euphoric hopes of his people. Overthrown after only six months in office, he successfully lobbied the Clinton administration to help him return to Haiti as president, where he would work to eliminate the power base of the old regime. Once back in the country, Aristide knew he would have to do something dramatic to outmaneuver his enemies, and he made a courageous but fateful decision that ultimately led to his undoing: He abolished the army that had terrorized the Haitian people for decades.

While Aristide was struggling to consolidate his position in Haiti, President Clinton was encountering strong resistance from Congress to his efforts to assist Aristide. Two months after the `94 intervention, Republicans captured both the Senate and the House, and new congressional leaders like Senate Foreign Relations Committee chairman Jesse Helms (R-N.C.) and House Speaker Newt Gingrich (R-Ga.) made it clear they did not approve of Clinton’s support for the reinstatement of Aristide, whose populist views they distrusted.

As a result, congressional appropriations for Haiti peacekeeping operations, police training, and other forms of basic “nation-building” assistance began to dry up long before the job was done. Even as the United States was scaling back its commitment to Haiti, however, the country registered a victory for democracy when Haitians went to the polls for their second presidential election in December 1995, choosing Rene Preval to succeed Aristide at the end of his constitutionally prescribed five-year term.

But trouble was brewing. With decreasing levels of international support, the growth of democracy in Haiti was stunted and the country’s traditional patterns of political violence and manipulation began to recur. After leaving office, Aristide was accused by his opponents of using his political movement, Lavalas, to foment intimidation and rig parliamentary elections. Having abolished the army, Aristide now began to encourage the formation of armed groups of his supporters, who were associated with the country’s rising level of human rights abuses.

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In 2000 Aristide became president again after an election that was boycotted by the opposition, who claimed the balloting was flawed. The opposition leaders were disorganized and intransigent, but their numbers grew and began to include former Aristide supporters disillusioned by signs that the president was abusing his power. Following the `00 election, the UN announced that it would cut back its mission in Haiti until the political crisis was resolved, and the European Union suspended its aid program. Haitian politics became sharply polarized. Aristide’s opponents in Haiti, as well as elements abroad associated with the old military regime, persuaded the incoming administration of George W. Bush to block all forms of assistance, including World Bank loans — a policy of economic strangulation that reflected the longstanding anti-Aristide views of the Republican Congress. The result was disastrous. From 2000-04, Haitians sank deeper into poverty, and their government became dysfunctional.

The stage was set for the crisis that engulfed Haiti last month. As leaders of the country’s officially disbanded army and murderous paramilitary groups seized control of provincial cities, opposition politicians, who claimed they had no connection to the marauding gangs, exploited the growing chaos to call for the ouster of the president. In response, Aristide requested the assistance of international troops to restore order. France announced that it would back an international peacekeeping force, but only if Aristide stepped aside. While still officially opposing Aristide’s ouster, a day later the Bush administration indicated it would not consider Aristide’s request for help in the absence of a “political solution.”

This should have been the time to send in the Marines. In light of the military success of the intervention 10 years earlier, it is likely that an international force could have stabilized Haiti and allowed the Caribbean Community (Caricom) to broker its proposal for Aristide to share power with the political opposition. When France and the United States declined to send troops, however, Aristide’s opponents were emboldened to reject the power-sharing proposal. At first, the Bush administration had supported the Caricom approach. But when armed gangs threatened Port-au-Prince and the opposition continued to insist on Aristide’s removal, President Bush backed down and pressured Aristide to leave. By failing to send troops earlier, and then pushing Aristide out the door, the United States effectively gave a green light to the second coup d’etat against him, despite having intervened a decade earlier to reverse the first one.

Following the events of last week, things are likely to go from bad to worse in Haiti unless the Bush administration quickly reverses its policy of strangling the country economically and standing by as it descends into anarchy. Sending in a thousand Marines by the end of this week, joined by several hundred Canadian, French, and Chilean troops, is a step in the right direction, but more troops are urgently needed. With reports of mounting violence and revenge attacks on Aristide supporters, Haiti is rapidly turning into a human rights catastrophe that could lead once again to a refugee crisis. In the week before the coup, hundreds of Aristide supporters tried to flee the country. If the past is any guide, these numbers will rise unless the security situation is brought under control.

In an age of terrorism, the United States cannot afford to have a failed state as a next-door neighbor, nor to have other Caribbean nations accuse it of undermining democracy in the region. This week Caricom called for an investigation by the UN of the circumstances under which Aristide left office, noting in a statement that what happened last week “set a dangerous precedent for democratically elected governments everywhere.”

It’s time to get serious about Haiti. If ever there were a situation requiring international assistance for nation-building, Haiti is such a case. While it may be too late for Aristide, it is certainly time to renew the commitment made by President Clinton a decade ago — but withdrawn under pressure from the Congress before it could begin to show results — to help the Haitians stabilize their country and revitalize their economy.

The United States will have plenty of allies in this effort if it demonstrates constructive leadership on Haiti. The UN, Caricom and the Organization of American States are all eager to renew the nation-building work to which they contributed earlier as they look to the United States to show whether its professed commitment to promoting democracy and human rights in the far more controversial cases of Afghanistan and Iraq will be extended to the impoverished nation in its own backyard. The weeks ahead will be decisive, as millions in Haiti and throughout the world watch for signs that the Bush administration is prepared to help solve rather than exacerbate the crisis in Haiti.

John Shattuck, CEO of the John F. Kennedy Library Foundation, served as President Clinton’s assistant secretary of state for democracy, human rights, and labor from 1993 to 1998 and as ambassador to the Czech Republic from 1998 to 2000. He is the author of “Freedom on Fire: Human Rights Wars and America’s Response” (Harvard).