A United Nations Security Council resolution passed last Sunday only approved the dispatch of troops by member countries. About 1,900 have arrived ? 1,200 Americans, 500 French, 130 Chileans and 60 Canadians. Canada pledged 390 more and Brazil has promised troops. The improvised American-led effort may grow to 5,000 soldiers, including about 2,000 marines, this month.

But there is no visible recruitment yet for a United Nations force. “The U.N. is not in the business of recruiting,” said Fred Eckhard, Mr. Annan’s spokesman. “If you want that, speak to the United States and its friends.”

Mr. Annan, under the resolution, has 25 days left to create a peacekeeping force. Until then, the United States is in charge. But as in Iraq, Afghanistan and the Balkans, it may prove easier for American troops to land in Haiti than to leave.

Raymond W. Kelly, now the New York police commissioner, strove to create a working force for law and order in Haiti a decade ago. But the national police dwindled to a force of less than 3,000, became dissolute and corrupt, and barely exists today.

To re-establish order, “clearly you need more resources than were ever talked about there” in the past, Mr. Kelly said. “You’d be talking roughly 20,000 police in Haiti.”

Training and equipping a force that size could take years.

The question of the Haitian Army also overshadows the country’s future. Mr. Aristide dissolved it in 1995; the armed rebels have announced its resurrection. The army was created by the American military after it occupied the country and imposed martial law in 1915.

Mary A. Renda, author of “Taking Haiti,” an award-winning history of the American occupation, said the Marines created “a military that was intended to be used against the Haitian people.”

The government is riven by factions. Beyond the rebels, whom the United States has told to lay down their arms, there remain loyal Aristide ministers and supporters, and the political opposition led by Haiti’s elites.

Many Aristide loyalists are still hiding from rebel death threats, and many elites supported the rebel cause ? the overthrow of Mr. Aristide and the reconstitution of the army, which has always served the elites at the expense of its poor.

Many of Haiti’s poor ? the millions who live on less than a dollar a day ? remain loyal to Mr. Aristide, who rose to power on his promises to deliver “peace in the mind, peace in the belly.” They wonder what role they will have in a new government.

“Look at how we are living,” said Sony Aurelien, a 33-year-old port inspector who lives in La Saline, the vast slum where Mr. Aristide served as a priest, gesturing at the open sewers overflowing with putrid garbage. “With Aristide, for the first time we have started to live. I am the first one in my family to have a regular job. Aristide tried to lift us up, so America kidnapped him and took him away.”

One model for Haiti today may be Liberia, the West African nation of former American slaves established with American support in 1821.

In Liberia, less then seven months ago, as rebels besieged the capital, 2,000 marines dropped anchor offshore and secured the airport for aid shipments. Small platoons patrolled the capital and quelled the rebels. In weeks, they handed off power to United Nations peacekeepers. Liberia is hardly healed, but $500 million worth of promised international aid and the peacekeepers have made a start.

Without law and order and a flood of economic aid, thousands more Haitian refugees may take to the seas, fleeing their failed state for Florida. The last time Haiti fell to an armed rebellion, in 1991, some 40,000 refugees washed up on American shores. During February, 1076 Haitians were intercepted by the United States Coast Guard.

Stopping refugees was a high priority in dispatching the Marines. “We will turn back any refugee that attempts to reach our shores,” President Bush said.

Some of those trying to flee Haiti are Aristide loyalists who fear for their lives. International law forbids returning political refugees to a place where they might be killed or jailed. In 1994, President Clinton created a “safe haven” for Haitian refugees at the nearby American naval base at Guantánamo Bay in Cuba. That base is now filled with suspected Islamic militants imprisoned by the United States.

Hunger and disease are rampant in Haiti, and the flow of international aid achingly slow. Many international aid agencies’ stores were looted during the rebel advance on the capital. “We have let Haiti slip back into a silent humanitarian emergency even before this period of extreme internal strife,” Jan Egeland, the United Nations’s chief aid coordinator, told the Security Council on Friday.

Saturday was market day in the capital, the first calm day for commerce in five weeks on the Rue des Miracles in downtown Port-au-Prince. But, given Haiti’s ruined economy, “normal is terrible,” said Mona Alexis, a street vendor selling cinnamon, ginger and star anise alongside hawkers of brake fluid, saddle shoes and cornflakes on the Street of Miracles.

“I haven’t sold a thing all day,” said Ms. Alexis, 41, the sole supporter of five children. “Nobody has any money. My family and I are barely surviving.”

United States military aircraft landed all Saturday afternoon at the international airport here, deepening the American presence in Haiti. They ranged from a 17-seat government executive jet to a gray hulking Air Force transport.

The transport jet touched down and, with its engines still running, its nose cone tilted up. Two dozen marines, three carrying laptop computers along with their weapons, walked down a ramp, blinking and squinting in the harsh sun.

United Nations officials plan to fly here next week to study Haiti’s needs, Mr. Eckhard said.

A long international occupation of Haiti “would be sad, but it’s necessary,” said Régine Santil, a Port-au-Prince shopkeeper. “We have proved through the years that we are incapable of running this country. But didn’t the Americans who brought Aristide back 10 years ago know that this day would come?”

Reporting for this article was contributed by Rachel L. Swarns, Eric Schmitt and Christopher Marquis in Washington, Warren Hoge at the United Nations and William K. Rashbaum in New York.