The United States is sending an extra 4,000 troops to Haiti to help in the relief effort after last week's magnitude 7.0 earthquake.
Officials said the sailors and marines were being diverting from scheduled deployments to Europe and the Middle East.
The announcement came as a big aftershock in the capital Port-au-Prince hampered relief efforts.
The US Geological Survey says the magnitude 5.9 aftershock struck just after 6am on Wednesday local time.
Witnesses say it lasted about 10 seconds, and sent people running into the streets in panic.
Some buildings which were already damaged are said to have collapsed in the latest tremor.
New Zealand aid
New Zealand is contributing another $1 million to support relief and recovery efforts in Haiti.
Foreign Affairs Minister Murray McCully says it is important that New Zealand be part of the international response.
Thursday's announcement brings the total amount of aid to $2 million.
More survivors found
The United Nations says more than 120 people have been rescued by international teams since the initial quake struck. They include a 69-year-old woman pulled from the ruins of a church in the capital.
A three-week-old baby girl has been pulled alive from a house in the town of Jacmel, more than a week after it collapsed in the earthquake.
She was found by a French team, in a hollow beneath the ruins of the building. The baby's uncle said she appeared to be healthy and uninjured.
Meanwhile, a US naval hospital ship has arrived off Haiti and is ready to begin taking on board the worst of the injured.
A US military spokesman says the USNS Comfort will treat 30 to 50 patients at a time, chosen by Haitian officials from the thousands in hospitals and makeshift clinics.
Officials in Haiti have estimated the death toll from the quake on 12 January could be between 100,000 and 200,000, and said 75,000 bodies had already been buried in mass graves.