The United States is withdrawing from UNESCO, the United Nation's cultural and educational agency, effective December 31, the US State Department has said in a statement.
- UNESCO is voting to choose a new director this week amid tensions over funding trouble and divisions over Palestine membership
- The US pulled out of UNESCO in the 1980s then joined again in 2003
- UNESCO is best known or its World Heritage program
"This decision was not taken lightly, and reflects US concerns with mounting arrears at UNESCO, the need for fundamental reform in the organisation, and continuing anti-Israel bias at UNESCO," the department said, adding that the United States would seek to "remain engaged … as a non-member observer state in order to contribute US views, perspectives and expertise."
While the US stopped funding UNESCO after it voted to include Palestine as a member in 2011, the State Department has maintained a UNESCO office at its Paris headquarters and sought to weigh in on policy behind the scenes.
UNESCO expressed regret over the United States' official decision to leave its organisation.
"After receiving official notification by the United States Secretary of State, Mr Rex Tillerson, as UNESCO Director General, I wish to express profound regret at the decision of the United States of America to withdraw from UNESCO," said UNESCO Director General Irina Bokova in a statement.
Ms Bokova added that the US decision marked a loss for multilateralism and for the UN family.
The announcement comes as UNESCO is voting to choose a new director this week, in tense balloting overshadowed by the agency's funding troubles and divisions over Palestinian membership.
Many saw the vote to include Palestine as evidence of long-running, ingrained anti-Israel bias within the UN, where Israel and its allies are far outnumbered by Arab countries and their supporters.
UNESCO is best known for its World Heritage program to protect cultural sites and traditions around the world. The agency also works to improve education for girls in desperately poor countries and in scientific fields, to promote better understanding of the horrors of the Holocaust and to defend media freedom, among other activities.
The Trump administration has been preparing for a likely withdrawal for months, and a decision was expected before the end of the year, according to US officials.
Several diplomats who were to have been posted to the mission this summer were told that their positions were on hold and advised to seek other jobs.
The US pulled out of UNESCO in the 1980s because Washington viewed it as mismanaged and used for political reasons, then re-joined the organisation in 2003.