Tropical storm Tomas is heading for Haiti after sweeping over the eastern Caribbean islands where it killed at least 12 people.
Tomas weakened to a tropical storm after hitting the islands, but forecasters say it is likely to pick up strength again over the central Caribbean.
In preparation for the storm's expected arrival at Haiti, the U.S. military has diverted the amphibious ship USS Iwo Jima from Suriname toward Port-au-Prince, where it could support humanitarian relief missions on short notice.
The hurricane-strength storm hit the resort island of St. Lucia Saturday, triggering landslides. Officials say they have confirmed at least 12 dead.
St. Lucia's Prime Minister Stephenson King declared a state of emergency in the island nation Tuesday, and asked for international aid.
The storm could pose a threat to Haiti, where hundreds of thousands of people are living in tents after a devastating earthquake in January.
The country is also struggling to contain a cholera outbreak that has killed more than 300 people.
Tuesday afternoon, the U.S. National Hurricane Center said Tomas was about 570 kilometers south-southeast of Port-au-Prince, with winds of 85 kilometers per hour.
United Nations agencies and other aid groups have ordered emergency supplies to be stockpiled across Haiti, especially in areas threatened by the storm.
The USS Iwo Jima carries 1,600 military and civilian medical, engineering, aviation and logistical support personnel. With its helicopters and flight deck, and ability to quickly move personnel and cargo, the ship is well-suited for humanitarian and disaster relief missions.
Some information for this report was provided by AP and AFP.