The United States is pulling out of Unesco after repeated criticism of resolutions by the UN cultural agency that Washington sees as anti-Israel.
Israeli Prime Minister Benjamin Netanyahu said Israel plans to follow suit.
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.
The withdrawal was confirmed on Thursday by US officials.
Unesco director-general Irina Bokova, who is Bulgarian, expressed “profound regret” at the decision and said the departure was a loss for “the United Nations family” and for multilateralism.
She said the US and Unesco matter to each other more than ever now because “the rise of violent extremism and terrorism calls for new long-term responses for peace and security”.
Ms Bokova defended Unesco’s reputation, noting its efforts to support Holocaust education and train teachers to fight anti-Semitism.
She traced the decades-long US ties with Unesco, and noted that the Statue of Liberty is among the many World Heritage sites protected by the UN agency.
Mr Netanyahu said on Thursday that Israel will also withdraw from the agency, which had become a “theatre of the absurd because instead of preserving history, it distorts it”.
He said he has ordered Israeli diplomats to prepare Israel’s withdrawal from the organisation in concert with the Americans.
Israel’s ambassador to the UN, Danny Danon, praised Washington’s move as heralding “a new day at the UN, where there is a price to pay for discrimination against Israel”.
He said: “Unesco has become a battlefield for Israel bashing and has disregarded its true role and purpose. The organisation’s absurd and shameful resolutions against Israel have consequences.”
Ms Bokova’s two terms as director have been deeply scarred by the 2011 Unesco vote to include Palestine as a member, funding troubles and repeated resolutions seen as anti-Israel.
Many saw the vote to include Palestine as evidence of long-running, ingrained anti-Israel bias within the United Nations, where Israel and its allies are far outnumbered by Arab countries and their supporters.
Unesco is best known for its World Heritage programme 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.
In addition, the Trump administration’s proposed budget for the next fiscal year contains no provision for the possibility that Unesco funding restrictions might be lifted.
The lack of staffing and funding plans for Unesco by the US have been accompanied by repeated denunciations of Unesco by senior US officials, including US ambassador to the United Nations Nikki Haley.
The US pulled out of Unesco in the 1980s because Washington viewed it as mismanaged and used for political reasons, then rejoined it in 2003.