Key dates in the US and UNESCO's on-again, off-again relationship

(Reuters) -Once again, the U.S. has said it will pull out of the United Nations culture and education agency UNESCO, with U.S. President Donald Trump repeating a move from his first term in office that his successor, Joe Biden, had reversed.

Here are some important dates in the sometimes tumultuous relationship between the U.S. and the United Nations Educational, Scientific and Cultural Organization:

* November 16, 1945:

UNESCO's founding treaty is signed and its constitution is adopted in London, saying it intends to advance "international peace" and "the common welfare of mankind."

* September 30, 1946:

The U.S. ratifies the UNESCO treaty, becoming one of its founding member states.

* June 1977:

The Fund for the Protection of the World Cultural and Natural Heritage of Outstanding Universal Value, also called the World Heritage Fund, is established under UNESCO. It provides millions of dollars to support conservation programs at UNESCO-designated sites.

* October 1979:

The first 45 sites are inscribed on UNESCO's World Heritage List, including three from the U.S.: the Grand Canyon in Arizona, Florida's Everglades National Park and Independence Hall in Philadelphia. 

* December 30, 1983:

U.S. President Ronald Reagan's administration announces that the U.S. is withdrawing from UNESCO, effective December 1984, saying it had become "politicized," financially mismanaged, unduly focused on weapons disarmament during the Cold War and hostile to free markets and a free press.

* October 1984:

The Statue of Liberty in New York Harbor and California's Yosemite National Park are inscribed on the World Heritage List.

* 1985–2003:

Despite the U.S. withdrawal, UNESCO continues to add U.S. sites and cultural heritages to the World Heritage List, including Hawaii Volcanoes National Park; Thomas Jefferson's home Monticello in Virginia and the Chaco Culture of the Pueblo people who occupied what is now a large region in the U.S. Southwest.

* April 1994:

U.S. Congress passes a law that blocks U.S. financing for any U.N. agency that accepts the State of Palestine as a full member.

* September 12, 2002: 

U.S. President George W. Bush announces in a speech to the UN General Assembly that the U.S. will rejoin UNESCO, citing leadership reforms in recent years as he sought to build international support for the Iraq War. It does so formally the following year.

* October 31, 2011:

UNESCO accepts Palestine as its 195th full member, despite the risk of losing U.S. funds, which at the time reportedly accounted for about 22% of UNESCO's budget. U.S. President Barack Obama's administration, which had unsuccessfully sought to get Congress to relax the 1994 financing law in the runup to the vote on Palestinian membership, ends U.S. funding.

* October 12, 2017:

Trump's administration announces the U.S. will once again leave UNESCO, this time for what it called "anti-Israel bias." The U.S. became a non-member observer.

* June 2023:

Biden's administration announces it will rejoin UNESCO, saying the agency had "modernized its management and reduced political tensions."

* July 22, 2025:

Trump's administration announces the U.S. again will leave UNESCO for the third time, because of his government's belief that it "supports woke, divisive cultural and social causes."  

(Compiled by Jonathan Allen; Editing by Don Durfee and Rod Nickel)