The U.S. military says it has taken control of the airport in the capital of earthquake-ravaged Haiti.
The U.S. military will help coordinate flights bringing in aid and evacuating foreigners and the injured.
U.S. Secretary of State Hillary Clinton is due to arrive in Haiti on January 16 to inspect the damage and meet with President Rene Preval and other officials.
U.S. President Barack Obama has pledged continued U.S. commitment to Haiti.
Medical teams, meanwhile, have set up makeshift hospitals, as workers started to clear the streets of corpses and water was being distributed in pockets of the city.
Aid workers and authorities warned that unless they can quickly get aid to the people, Port-au-Prince will degenerate into lawlessness.
There were reports of isolated looting, but U.S. Secretary of Defense Robert Gates said the overall security situation remains calm.
The Red Cross estimates up to 50,000 people were killed in the January 12 earthquake.