The United States and Israel officially quit of the UN's educational, scientific and cultural agency, citing bias against Tel Aviv.
The withdrawal became official at midnight, putting an end to a process triggered more than a year ago, reported The Associated Press.
The Trump administration filed its notice to withdraw in October 2017 and Israeli Prime Minister Benjamin Netanyahu followed suit.
The withdrawal is mainly procedural yet serves a new blow to UNESCO, co-founded by the US after World War II to foster peace.
The US has demanded "fundamental reform" in the agency that is best known for its World Heritage program to protect cultural sites and traditions. UNESCO also works to improve education for girls, promote understanding of the Holocaust's horrors, and to defend media freedom.
The Paris-based organization has been critical of Israel's occupation of East Jerusalem, naming ancient Jewish sites as Palestinian heritage sites and granting full membership to Palestine in 2011.
It also voted in Palestine as a member in 2011, prompting both Israel and the US to stop paying dues.
Since then officials estimate that the US — which accounted for around 22 percent of the total budget — has accrued $600 million in unpaid dues, which was one of the reasons for President Donald Trump's decision to withdraw. Israel owes an estimated $10 million, said the AP.
UNESCO Director General Audrey Azoulay took up her post just after Trump announced the pullout.
Azoulay, who has Jewish and Moroccan heritage, has presided over the launch of a Holocaust education website and the UN's first educational guidelines on fighting anti-Semitism — initiatives that might be seen as responding to US and Israeli concerns.
Officials say that many of the reasons the US cited for withdrawal do not apply anymore, noting that since then, all 12 texts on the Middle East passed at UNESCO have been consensual among Israel and Arab member states.
The United States has pulled out of UNESCO before. The Reagan administration did so in 1984 because it viewed the agency as mismanaged, corrupt and used to advance Soviet interests. The US rejoined in 2003.
