The United States will leave the World Health Organization on Jan. 22, 2026, the United Nations said on Thursday, after being formally notified of the decision by President Donald Trump, who has accused the agency of mishandling the pandemic and other international health crises.

Trump announced the move on Monday, hours after he was sworn in for a second four-year term. The WHO said on Tuesday that it regretted the move from its top donor country.

Trump must give a one-year notice of U.S. withdrawal from the Geneva-based body and pay Washington's dues under a 1948 joint resolution of the U.S. Congress.

The United States is by far the WHO's biggest financial backer, contributing around 18% of its overall funding. WHO's most recent two-year budget, for 2024-2025, was $6.8 billion. It was not immediately clear how much the U.S. owes.

"I can confirm we have now received the U.S. letter on the WHO withdrawal. It is dated 22 January 2025. It would take effect a year from yesterday, on 22 January 2026," said deputy U.N. spokesperson Farhan Haq.

The U.S. departure will likely put at risk programs across the organization, according to several experts inside and outside the WHO, notably those tackling tuberculosis, the world’s biggest infectious disease killer, as well as HIV/AIDS and other health emergencies.

The withdrawal order signed by Trump said the administration would cease negotiations on the WHO pandemic treaty while the withdrawal is in progress. U.S. government personnel working with the WHO will be recalled and reassigned, and the government will look for partners to take over necessary WHO activities, according to the order.

Trump's withdrawal from the WHO was not unexpected. He took steps to quit the body in 2020 during his first term as president. Before the U.S. withdrawal could be completed last time, Joe Biden won the presidential election and put a stop to it on his first day in office on Jan. 20, 2021.