As well as accusing UNESCO of bias, the U.S. state department said it was also concerned about mounting financial arrears at the agency and said it should be reformed.
A press statement from the State Department says the decision was also based on "the need for fundamental reform in the organization" as well as stacking up bills the USA owes UNESCO.
The withdraw becomes official on December 31, 2018, after which the United States will remain involved as a nonmember observer state.
"Despite the withholding of funding, since 2011, we have deepened the partnership between the United States and UNESCO, which has never been so meaningful", she underscored.
UNESCO, officially the United Nations Educational, Scientific and Cultural Organization, is known mainly for naming and overseeing World Heritage Sites, a list that includes over 1,000 protected natural and built environments of great importance to humanity.
The country plans to become "a non-member observer state in order to contribute USA views, perspectives and expertise on some of the important issues undertaken by the organization, including the protection of world heritage, advocating for press freedoms, and promoting scientific collaboration and education".
"The goal of UNESCO is a good one", US Ambassador to the United Nations Nikki Haley said in a statement. The U.S. stopped making payments to the agency in 2011, but maintained an office at its Paris headquarters in the hopes of encouraging a change of course from behind the scenes.
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They had been put in plastic bags, along with a knife and " heavy metal pieces " to make them sink. Bags found just one kilometer from the place where, on 21 August, found the torso of a woman.
Nauert said the state department had notified Bokova of their decision earlier on Thursday.
The US stopped paying dues to the global body in late 2011 after the agency voted to accept a Palestinian bid for full membership and now owes approximately $550 million, a State Department spokesperson said.
Under the Reagan Administration, the U.S. quit UNESCO in 1984, at the time accusing the agency of a pro- Soviet Union bias.
In July, Unesco declared the ancient and hotly contested core of Hebron, in the Israeli-occupied West Bank, as a Palestinian World Heritage site in danger, a decision sharply criticized by Israel and its allies.
The third round saw the breakthrough of French candidate Audrey Azouley, who secured 18 out of 58 votes of the UNESCO Executive Board, sharing top spot with Qatari candidate Hammad bin Al-Kawari. It referred to the holy site only using Muslim names and prompted angry reactions from Israeli politicians.
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.