The United States military is intensifying its aid and security operations in Haiti in the wake of last week's devastating earthquake.
United Nations officials said aid distribution points were being set up in the capital, Port-au-Prince, and UN security forces will accompany US troops as they deliver supplies, the BBC reports.
Helicopters dropped scores of US paratroopers in the presidential palace grounds, who then moved to secure a nearby hospital. The US navy has also sent helicopters to the airport at the city of Jacmel, which was previously isolated, carrying water and food.
Officials are considering whether airdrops should be used throughout Haiti. The US military says areas are being secured before pallets of food and water are parachuted in, to avoid the risk of riots.
The UN Security Council has voted to boost its peacekeeping forces by another 3,500 troops and police, to help control outbursts of looting. Anger has been growing in the streets of Port-au-Prince as people wait for help.
Some 14,000 food parcels and 15,000 litres of drinking water have already been dropped to a secure area near the city.
The American army says Port-au-Prince's airport is now handling 180 flights a day, compared with 30 flights a day before it was damaged.
Too long to wait - aid organisation
An aid organisation helping survivors says injured people in the capital are still having to wait too long for assistance. Doctors Without Borders says many of the people its doctors are treating require amputations because their wounds have become infected.
A pediatrician working at a makeshift United Nations hospital, Delphine Rowbotham, told the BBC many children need to be transferred overseas for treatment.