The US is sending another 4,000 sailors and marines to Haiti for the earthquake relief effort, diverting them from deployments in the Gulf and Africa.
The 24th Marine Expeditionary Unit and USS Nassau Amphibious Ready Group would “significantly” increase the ability to quickly provide aid, the navy said.
The move will increase the number of US troops involved to about 16,000.
Earlier, a strong aftershock rocked the capital, Port-au-Prince, but did not seem to cause further casualties there.
Away from the city, survivors in some towns are still waiting for help after the original 7.0-magnitude earthquake struck eight days ago.
The only outside medical help it had seen was a team of Dominican and Spanish doctors who were setting up a treatment centre.
He said the village had been left looking worse than most war zones – as if it had been carpet-bombed, then pounded with a relentless artillery barrage.
Haitian officials say the death toll from the quake was likely to be between 100,000 and 200,000, and that 75,000 bodies had already been buried in mass graves. An estimated 1.5 million are homeless.
People are still being found alive in the rubble, including a five-year-old boy reportedly pulled from the ruins of his home by his uncle. Earlier a 10-year-old girl and her eight-year-old brother were found.
More than 120 people altogether have been rescued by international teams.