Hillary Clinton told the International Aids conference yesterday that the United States remains determined to eradicate the disease even as the search for a vaccine and a cure continues.
But warnings were sounded that progress made so far could be reversed by a fall-off in funding caused by the economic slowdown.
"The US is committed and will remain committed to creating an Aids-free generation: we will not back down," the US Secretary of State told delegates at the start of the five-day meeting.
Aware of the concern that money for research and treatment around the world is at risk of drying up, she added: "We will fight for the resources necessary to achieve this historic milestone."
Anthony Fauci, the head of Aids research at the National Institutes of Health, said later: "Obviously when there are constrained resources there is some impact on your ability to implement." One solution, he said, was to "bring in more countries that have not yet participated very robustly". He noted that Japan, Germany and Saudi Arabia had recently stepped up contributions.