The United States will end its relationship with the World Health Organization (WHO) over the body's handling of the coronavirus pandemic, U.S. President Donald Trump said on Friday.

Speaking in the White House Rose Garden, Trump asserted that the agency had pressured to "mislead the world."

"Because they have failed to make the requested and greatly needed reforms, we will be today terminating our relationship with the World Health Organization and redirecting those funds to other worldwide and deserving urgent global public health needs," Trump said.

It was not immediately clear when his decision would come into effect. A 1948 joint congressional resolution on U.S. membership of the WHO said the country "reserves its right to withdraw from the organization on a one-year notice."

The United States currently owes the WHO more than 200 million dollars in assessed contributions, according to the WHO website. On May 19, Trump sent a four-page letter to WHO Director-General Tedros Adhanom Ghebreyesus, warning he would permanently cut U.S. funding of the WHO and reconsider U.S. membership if the organization did "not commit to major substantive improvements within the next 30 days."

The WHO did not immediately respond to a request for comment on Trump's announcement.

Health experts, U.S. lawmakers and world leaders have expressed concern over defunding the organization amid a pandemic.

Patrice Harris, president of the American Medical Association, criticized Trump's announcement Friday, saying they were "senseless" and had "significant, harmful repercussions." 

"COVID-19 affects us all and does not respect borders; defeating it requires the entire world working together," Harris said in a statement. "In the strongest terms possible, the American Medical Association urges the President to reverse course and not abandon our country's leadership position in the global fight against COVID-19."

Amesh A. Adalja, a senior scholar at the Johns Hopkins Center for Health Security, said in practice, Trump's decision was unlikely to change the operations of the WHO. 

"From a symbolic or moral standpoint it's the wrong type of action to be taking in the middle of a pandemic and seems to deflect responsibility for what we in the U.S. failed to do and blame the WHO," said Adalja. 

Senator Lamar Alexander of Tennessee, chair of the Senate Health, Education, Labor and Pensions Committee, said, "I disagree with the president's decision." 

"Certainly there needs to be a good, hard look at mistakes the World Health Organization might have made in connection with coronavirus, but the time to do that is after the crisis has been dealt with, not in the middle of it," Alexander said in a statement.

Russian Foreign Ministry spokeswoman Maria Zakharova criticized the U.S.'s decision, describing it as trampling on the international legal basis for world health cooperation at a time when the world is needed to unite against the novel coronavirus.

"What can the United States offer to the world in return? The sad picture in the U.S. public health system, exposed by the pandemic, does not leave Washington a single chance to claim its leadership in this sphere," she said.