The United States on Thursday began flying military helicopter relief missions to Pakistan's northwestern regions devastated by worst floods in living memory, the US embassy said.
"Between them four Chinook and two Blackhawk helicopters flew up to 18 sorties today and dropped 66,000 pounds of relief supplies and evacuated more than 800 people from Kalam," spokesman Richard Snelsire told AFP.
The helicopters came over from Afghanistan, where nearly 150,000 US-led NATO troops are fighting against a nearly nine-year Taliban insurgency.
US government helicopters, which are manned by a Pakistani crew, have been operating in the country since Friday, rescuing over 900 people.
American crew operate the military flights in the presence of a Pakistani military representative, the embassy said.
Pakistan began evacuating half a million people from flood-risk areas in the south on Thursday as the overall number hit by the country's worst floods in living memory rose to more than four million.
Anti-Americanism is rife in Pakistan with widespread public opposition to the government's alliance with the United States.
A covert US drone war against Taliban and Al-Qaeda militants in Pakistan's semi-autonomous tribal belt has inflamed public sentiment in the northwest.