Kalam, Pakistan ? U.S. Army choppers carrying emergency food and water buzzed over the swollen river and washed-out bridges, landing in the valley once controlled by the Taliban. They returned laden with grateful Pakistani flood survivors — newly won friends in a country where many regard America as the No. 1 enemy.

With Pakistan reeling from two weeks of flooding that has killed 1,500 and affected nearly 14 million people, the aid and rescue mission by the U.S. military gives Washington a chance to strengthen a sometimes troubled alliance that is crucial to fighting militancy in the region and ensuring a stable Afghanistan.

Besides helping those trapped by the high water, the U.S. assistance already is having another effect: The Pakistani Taliban denounced it and urged a boycott of Western aid.

Other U.S. relief missions to disasters in the Muslim world — including the 2005 earthquake in Pakistan-controlled Kashmir and the 2004 tsunami in Indonesia — were credited with improving the image of the United States, at least in the short term.

The United Nations said hundreds of millions of dollars in international assistance would be needed. In Washington, the State Department announced an additional $20 million in flood relief, bringing the total U.S. aid in the crisis to $55 million.