US marines have begun arriving in the Philippines to help with disaster relief efforts in the country.
The marines are taking tents, generators and medical supplies
Floods and landslides following four violent storms in two weeks have left about 1,000 people dead or missing.
Some 40 marines, the first of a total of up to 600 troops, have arrived at a former US base north of Manila.
The US said the move was in response to a request from the Philippine government, which says the storms have wreaked millions of dollars of damage.
Up to a dozen transport aircraft and helicopters are accompanying the troops, the Pentagon said in a statement.
"This is a serious endeavour. The safety and well-being of the Filipinos are a top priority and we're responding as best we can in as speedy and effective a way," said US military spokesman Dennis Williams.
The BBC's Nick Childs at the Pentagon says the US and the Philippines maintain a strong alliance and close friendship.
The Philippines has co-operated in the Bush administration's global war on terrorism and the US has sent forces to help train and support the Philippine military.
"Our primary concern is to rapidly reduce the further loss of life and human suffering, and to enable Philippine forces to conduct sustained disaster management efforts," the Pentagon said.
"US forces will only remain as long as necessary for the Philippines to conduct sustained disaster relief operations."
Some 200,000 people were forced to flee from their homes when violent storms swept across north-eastern provinces.
Many areas are now isolated, only accessible by helicopter.
Marines and navy personnel began leaving their Japanese base in Okinawa late on Tuesday, taking potable water, medicine, blankets and generators with them.
Two US navy Seahawk helicopters have begun ferrying food and medical supplies into Real, one of the worst-affected areas, and carrying survivors to Manila, the AFP news agency reports.
A seven-man specially trained "lifesaver team" has also arrived to help storm casualties.