President Donald Trump said the US will sever ties with the World Health Organisation.
It comes after he accused WHO of failing to provide accurate information on the coronavirus pandemic.
Earlier this month he had threatened WHO with a permanent freeze.
On Friday, speaking in the Rose Garden at the White House, Mr Trump made the announcement claiming that it was due to China having “total control” over the global health organisation.
He said Chinese officials “ignored” their reporting obligations to the WHO and pressured the WHO to mislead the world when the virus was first discovered.
He noted that the US contributes around $450 million to the world body while China provides about $40 million.
The US is the largest source of financial support to the WHO and its exit is expected to significantly weaken the organisation.
Mr Trump said the US would be “redirecting” the money to “other worldwide and deserving urgent global public health needs,” without providing specifics.
The news comes as the US death toll from Covid-19 grew to over 100,000.
On May 19 he had posted a letter on Twitter saying the international agency must demonstrate “independence from China” and enact sweeping reforms within 30 days to secure a reinstatement of US funding.
“If the World Health Organisation does not commit to major substantive improvements within the next 30 days, I will make my temporary freeze of United States funding to the World Health Organisation permanent and reconsider our membership in the organisation,” Mr Trump wrote in the letter to WHO Director General Tedros Adhanom Ghebreyesus.
Mr Trump already made the decision to temporarily stop funding to the WHO on April 14, accusing the group of being too supportive of China.
He has also repeatedly accused the UN health body of mismanagement of the crisis, a claim repeated in the letter, which included bullet points laying out his dissatisfaction.
WHO has said it would launch an independent review of the response to the coronavirus pandemic.
Half of the WHO's funding is made up of annual donations by member states, and topped up by voluntary donations and funding from other bodies.
The US has contributed about 20 per cent of the WHO's overall budget over the past two years.
