The US has publicly declared it will fight discrimination against gays and lesbians abroad by using foreign aid and diplomacy to encourage reform.
Secretary of State Hillary Clinton told an audience of diplomats in Geneva: "Gay rights are human rights".
A memo from the Obama administration directs US government agencies to consider gay rights when making aid and asylum decisions.
Similar policies already exist for gender equality and ethnic violence.
"It should never be a crime to be gay," Mrs Clinton said at the United Nations in Geneva, adding that a country's cultural or religious traditions was no excuse for discrimination.
Her audience included representatives from countries where homosexuality is a criminal offence.
Many ambassadors rushed out of the room as soon as Mrs Clinton finished speaking, the Associated Press news agency reported.
In October, UK Prime Minister David Cameron's suggestion that aid could be cut to countries that did not recognise gay rights was condemned by several African countries where homosexual acts are banned, including Ghana, Uganda and Zimbabwe.
Last week Nigeria became the latest African country attempting to tighten homosexuality laws, with the Senate passing a bill banning same-sex marriages. Before it becomes law, it must be passed by the lower chamber and then signed by the president.
The announcement, described by the White House as the "first US government strategy to combat human rights abuses against gays and lesbians abroad", is also being seen as part of the Obama administration's outreach to gays and lesbians ahead of the 2012 election.
The official memorandum does not outline consequences for countries with poor records on gay rights. But it allows US agencies working abroad to consult with international organisations on discrimination.
"Gay people are born into and belong to every society in the world," Mrs Clinton said in Geneva. "Being gay is not a Western invention. It is a human reality."
Correspondents say the new policy could pose awkward questions for US officials formulating policy towards some regular allies and regional powers.
In 2011, the state department's annual human rights report cited abuses against gay people in Saudi Arabia, an ally of the US that bans homosexuality outright.
Afghanistan also prohibits homosexual activity, and the same report found that authorities "sporadically" enforced the prohibition.
In the US, Republican presidential candidates criticised the administration's decision, with Texas Governor Rick Perry saying in a statement that "promoting special rights for gays in foreign countries is not in America's interests and not worth a dime of taxpayers' money".
Mrs Clinton acknowledged the US had its own mixed record on gay rights. As late as 2003, some states had laws that made gay sex a crime.
Earlier this year President Barack Obama signed into law a bill repealing the "don't ask don't tell" law and allowing homosexuals to serve openly in the US military.