A logo is pictured at the World Health Organization (WHO) in Geneva, Switzerland, December 14, 2022. (Denis Balibouse/Reuters via CNN Newsource)

(CNN) โ€” President Donald Trump announced Monday he is withdrawing the US from the World Health Organization, in a significant move that drew criticism from public health experts on his first day back in the White House.

Trump has long been critical of the United Nationsโ€™ health agency, and his administration formally began a withdrawal from the WHO in July 2020 as the Covid-19 pandemic continued to spread. But four years ago, then-President Joe Biden halted the USโ€™ exit from the body tasked with coordinating the international response to health emergencies in one of his first actions after taking over the White House.

The text of Mondayโ€™s executive order cites the โ€œorganizationโ€™s mishandling of the COVID-19 pandemic that arose out of Wuhan, China, and other global health crises, its failure to adopt urgently needed reforms, and its inability to demonstrate independence from the inappropriate political influence of WHO member states,โ€ as reasons for the US withdrawal.

โ€œThatโ€™s a big one,โ€ Trump told an aide as he began to sign the executive order, pointing to his 2020 decision and his belief that the US was paying too much money to the organization compared to other countries. In 2020, Trump also consistently accused the organization of aiding China in allegedly covering up the origins of Covid-19 and allowing its spread.

CNN has reached out to the WHO for comment.

While lawmakers from both parties had criticized the WHO in 2020 when Trump first decided to pull out, many denounced the presidentโ€™s decision to withdraw during a once-in-a-century global pandemic. Then-House Speaker Nancy Pelosi at the time called it โ€œan act of true senselessness.โ€ And since-retired Republican Sen. Lamar Alexander โ€” then-chairman of the Senate Health, Education, Labor and Pensions Committee โ€” said he disagreed with Trumpโ€™s decision.

Dr. Ashish Jha, who served as White House Covid-19 response coordinator during the Biden administration, called Trumpโ€™s decision to withdraw from the WHO in his second term a โ€œstrategic error.โ€

โ€œWHO is a pretty essential organization โ€” and with Americaโ€™s withdrawal, it creates a political vacuum that only one country can fill โ€” and that is China,โ€ Jha said in an interview with CNN on Monday.

He predicted that China will step up for the organization in the absence of US funding and leadership, which could, in turn, โ€œgive China more political influence around the world.โ€

Lawrence Gostin, a public health law professor at Georgetown University, said in a post on X that Trumpโ€™s pulling out of the WHO is โ€œthe most momentous of allโ€ of Trumpโ€™s executive actions Monday.

โ€œItโ€™s a cataclysmic presidential decision. Withdrawal is a grievous wound to world health, but a still deeper wound to the US,โ€ he added.

Jha warned that withdrawing from the WHO weakens the organization because it relies heavily on US staff and expertise, particularly in tracking global influenza.

Trumpโ€™s executive action calls on the secretary of state and the director of the Office of Management and Budget to โ€œpause the future transfer of any United States Government funds, support, or resourcesโ€ for the WHO. However, it takes a year to fully withdraw from the body, and there is an obligation for the US to continue funding it for a year.

โ€œBut whoโ€™s going to enforce the obligation? Is Donald Trump going to be cowed by global norms around these things?โ€ Jha asked.

Gostin, who is also the Oโ€™Neill Chair in Global Health Law at Georgetown Law, said in a later post that the action is โ€œriddled with legal & factual errors.โ€

โ€œTrump isnโ€™t waiting a year as Congress required. Heโ€™s unraveling US engagement & funding now. Thatโ€™s unlawful & a grave strategic error,โ€ he added.