As of January 1, 2019, the United States has officially withdrawn from the United Nations Educational, Scientific, and Cultural Organization (UNESCO), one of the world’s best-known global cultural heritage and preservation organizations.

The withdrawal was first announced in October 2017 after UNESCO recognized the old city of Hebron in the West Bank as a Palestinian World Heritage Site amid fierce resistance from the United States and Israel. The old city of Hebron is home to, among other relics and cultural sites, the Tomb of the Patriarchs, a sacred religious site known as the Cave of Machpelah to Jews and as the Sanctuary of Abraham to Muslims. At the time, the United States and Israel complained that the UN was engaging in “anti-Israeli bias” stemming from the recognition of Palestine as a member state of the UN in 2011. Previously, the UN had criticized Israel’s occupation of East Jerusalem, according to Al Jazeera.

When the UN elevated Palestine to membership status in 2011–during the Obama administration—the United States stopped paying its membership dues to UNESCO in protest. By 2017 the past-due fees had grown to $570 million, The Washington Post reported, and then-Secretary of State Rex Tillerson decided to initiate the process of formal withdrawal from the organization. As of 2019, the outstanding balance due to UNESCO has risen above $600 million.

Following the withdrawal, Irina Bokova, director-general of UNESCO, said, “At the time when the fight against violent extremism calls for renewed investment in education, in dialogue among cultures to prevent hatred, it is deeply regrettable that the United States should withdraw from the United Nations leading these issues.”

The current episode marks the second time the United States has left UNESCO, following President Ronald Reagan’s withdrawal from the group in 1984 in an effort to thwart the recognition of Soviet historical sites. The United States rejoined the group in 2002 under President George W. Bush following the attacks of 9/11 amid a push to boost international solidarity by the U.S.

The United States now hopes it can participate as an “observer state” on “non-politicized issues,” including the protection of World Heritage sites. The body is due to take up this new role for the United States when it next meets in April 2019.