The tsunami that struck on Sunday spread a ring of destruction that stretches from Southeast Asia to Africa. Relief efforts continue to grow, with many countries, including the United States, promising even more assistance in the weeks and months ahead.

Food, medicine and other desperately needed items have started to arrive in countries hardest hit by the tsunami, in what the United Nations describes as the largest relief operation the world has ever seen.

The global body has sent disaster assessment teams to the affected countries and relief organizations are distributing supplies.

Andrew Natsios, Administrator of the U.S. Agency for International Development, says the technical teams play a critical roll assessing the precise help that will do the most good. "We must respond to the needs assessed by technical experts on the ground or we are going to kill people. Rumors do not help us provide assistance to people. Only reports from technical experts will be used to make these judgments."

Dozens of countries and relief groups around the world have already pledged tens of millions of dollars. In addition, many nations are sending emergency supplies directly to the disaster zones.

Ed Fox, Assistant Administrator of the U.S. Agency for International Development, told VOA that emergency supplies prepositioned by the United States began arriving in the affected areas on Wednesday.  "Planes loaded with plastic sheeting for shelter, with water bladders and water cans to get fresh water to people, with healthcare supplies and things of that nature. And, tragically, also with body bags for the sad aspects of this tragedy, the loss of human life."

In addition, the Pentagon is sending aircraft and naval vessels for the relief effort. According to General James Conway, Director of Operations for the Joint Chiefs of Staff, several ships are equipped with desalination equipment. "Each ship can produce 90,000 gallons of fresh water a day, and, of course, that will be extremely valuable as we have a number of requests already for fresh water supplies."

With such widespread destruction, relief workers are racing to prevent an outbreak of disease and famine among the millions of homeless.  Jan Egeland, the U.N.’s Emergency relief coordinator, says disease could kill as many as the tsunami. "Still, the biggest challenge is the water and the sanitation, and the emergency food and the emergency shelter for hundreds of thousands of homeless."

Mr. Egeland estimates the disaster will cost billions of dollars. He said the world body will issue a formal appeal for international contributions next week.