US President George W. Bush assembled a four-nation coalition to organize humanitarian relief for Asia and made clear the US will help bankroll long-term rebuilding in the region leveled by a massive earthquake and tsunamis.
US officials braced for the death toll to exceed 100,000.
"It's just beyond our comprehension to think about how many lives have been lost," Bush said Wednesday after emerging from a holiday vacation at his Texas ranch to make his first comments on the four-day-old disaster.
US embassy officials continued to hunt for 2,000 to 3,000 Americans who remain unaccounted for, and asked travelers to check in with families and US diplomatic posts. At least 12 Americans are known dead from Sunday's quake and subsequent tsunamis that struck a dozen countries from Thailand to Somalia.
From airlifts of rice and water purifiers to the deployment of an entire Marine expeditionary force, the US marshaled resources across the globe to augment its initial US$35 million aid package and make sure the hardest hit locations got the short-term help they requested.
Bush said he phoned the leaders of stricken countries to solicit specific needs and assure them the initial aid package "is only the beginning of our help." He also laid the foundation for a long-term international recovery plan by forming the coalition with Japan, Australia and India and inviting other nations to join.
"We will prevail over this destruction," Bush promised.
Eventually, US Secretary of State Colin Powell told BBC, "this core will expand and the entire international community will be involved to include the European Union" and take up such issues as debt relief for hard-hit countries.
Both the president and officials in Washington made high-profile efforts to tout the breadth of US aid, ticking off figures they hoped would rebut comments by a UN official and others suggesting that the US had been stingy or slow to react.
The president called the UN official's comments Monday "very misguided and ill informed." His State Department spokesman was more blunt: "We don't have anything to apologize for," Richard Boucher said.
During his holiday vacation at his ranch where he was riding his bike and clearing brush, Bush offered condolences to those half-a-globe away struck by the unprecedented death and destruction.