The United States has decided to withdraw from UNESCO, effective December 31, 2018. Hours after the announcement, which cited “anti-Israel bias” as the cause, Israel also vowed to leave the organization.

The United Nations Educational, Scientific and Cultural Organization, or UNESCO, was founded after World War II in an effort to promote global solidarity and cooperation through its mission to preserve culture, improve access to education, further gender equality, and promote scientific advances and freedom of expression. One of UNESCO’s most popular projects is the World Heritage program, which aims to identify and protect natural and cultural sites of great value to the existing world.

The most profound grievance cited by the U.S. centers around UNESCO’s decision to designate the city of Hebron in the West Bank, including its Tomb of the Patriarchs (also known as the Cave of the Patriarchs), as a Palestinian World Heritage site. Jewish people believe the site to be where Abraham, Issac, Jacob, and their wives were buried, and it is due to this religious significance that the area is important to Israel. Previously, in 2015, UNESCO passed a resolution that condemned “Israeli aggressions and illegal measures against freedom of worship” and criticized Israel for mishandling heritage sites in Jerusalem, according to The New York Times.

Palestinians and Israeli have been engaged in a longstanding conflict, with Israeli forces being accused of engaging in war crimes against Palestinian people, according to Amnesty International.

On the nation's departure from UNESCO, a U.S. official told The Washington Post that the decision “sends a strong message that we need to see fundamental reform in the organization, and it raises everyone’s awareness about continued anti-Israel bias.”

The United States has been distancing itself from UNESCO for years. In 2011, the U.S. cut its funding to UNESCO after the organization’s decision to grant full membership to Palestinians. At that time, White House spokesman Jay Carney said the vote was “premature and undermines the international community’s shared goal of a comprehensive, just and lasting peace in the Middle East,” according to the BBC.

The 2011 funding cut led to an accumulation of debt, as the U.S. was continually charged by the organization. The United States now owes more than $500 million.

The State Department has said the U.S. hopes to remain engaged with UNESCO as a nonmember observer state, which means the U.S. would be potentially allowed to participate in discussions, but would not be able to vote on issues.

This withdrawal has come amidst UNESCO members voting on a new director-general. The race is between Qatar’s Hamad bin Abdulaziz al-Kawari, France’s Audrey Azoulay, and Egypt’s Moushira Khattab. Both U.S. Jewish groups and Israeli officials have expressed concern for the current front-runner, Kawari, for “fostering anti-Semitism.”

The United States has withdrawn from UNESCO in the past under the Reagan administration in 1984 for fear of corruption within the agency and bias toward the Soviet Union. In 2002 the United States rejoined in an effort to show international solidarity and unity.

Nikki Haley, the U.S. ambassador to the United Nations, said in a statement, “Just as we said in 1984 when President Reagan withdrew from UNESCO, U.S. taxpayers should no longer be on the hook to pay for policies that are hostile to our values and make a mockery of justice and common sense.”