US President Donald Trump speaks about the coronavirus situation, at the Rose Garden of the White House, in Washington, April 14, 2020. (ALEX BRANDON / AP)

WASHINGTON./UNITED NATIONS - US President Donald Trump announced on Tuesday that his administration was halting the nation's funding to the World Health Organization (WHO), a move experts have warned against as COVID-19 continues to take a toll globally.

Speaking to reporters at the White House, Trump also said a review is being conducted to assess the WHO's role in addressing the spread of the coronavirus.

Now is the time for unity and for the international community to work together in solidarity to stop this virus and its shattering consequences.

Antonio Guterres, UN secretary-general

The announcement came as Trump is aggressively defending his own handling of the outbreak in the United States after the administration has been scrutinized for downplaying the threat from the coronavirus early on and faulted for delays in testing.

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The tone also differed from one of his tweets on Feb 24, several days before the United States reported the first death from COVID-19.

"The Coronavirus is very much under control in the USA," Trump wrote at that time. "We are in contact with everyone and all relevant countries. CDC & World Health have been working hard and very smart."

United Nations Secretary-General Antonio Guterres said the WHO must be supported, shortly after Trump's announcement.

"It is my belief that the World Health Organization must be supported, as it is absolutely critical to the world's efforts to win the war against COVID-19," Guterres said in a statement issued by his spokesman.

It is "not the time to reduce the resources for the operations of the World Health Organization or any other humanitarian organization in the fight against the virus," Guterres said.

The UN chief noted that "now is the time for unity and for the international community to work together in solidarity to stop this virus and its shattering consequences".

"Once we have finally turned the page on this epidemic, there must be a time to look back fully to understand how such a disease emerged and spread its devastation so quickly across the globe, and how all those involved reacted to the crisis," he said. "The lessons learned will be essential to effectively address similar challenges, as they may arise in the future."

Guterres also recalled the statement that he made on April 8, where he said that "the COVID-19 pandemic is one of the most dangerous challenges this world has faced in our lifetime. It is above all a human crisis with severe health and socio-economic consequences" and the WHO is supporting member states and their societies, especially the most vulnerable among them, "with guidance, training, equipment and concrete life-saving services" as they fight the virus.

Meanwhile, Lawrence Gostin, director of the O'Neill Institute for National and Global Health Law at Georgetown University, called cutting funding to the WHO during a global health crisis "disgraceful," warning that it would cause death and even blow back on the United States.

"How shortsighted when global coop needed more now than ever," Gostin said in a series of tweets on Tuesday.

In remarks delivered from Geneva last week, WHO Director-General Tedros Adhanom Ghebreyesus said, "We must quarantine politicizing this virus at national and global levels."

"We have to work together, and we have no time to waste," he added.

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According to a tally from Johns Hopkins University on Tuesday, the United States has reported more than 600,000 confirmed cases of COVID-19 and 25,575 deaths, both the highest on record.

Globally, the number of cases is approaching 2 million, as the death toll has surpassed 125,000, the tally showed.