What does the order say?

The order says the US was withdrawing “due to the organization’s mishandling of the Covid-19 pandemic”.

Trump’s longheld antipathy towards the WHO is rooted in a perception that it was dominated by – and so soft on – China, which the president has long believed was responsible for the spread of the virus.

It also mentions “unfairly onerous payments” the US made to the WHO.

What are the roadblocks?

It is the second time Trump has ordered the US be pulled out of the WHO. He began the process and Biden later reversed the decision after taking office.

The US exit won’t take effect until 2026 at the earliest, but leaving will require the approval of Congress.

On paper, the Republicans have a majority in both houses of Congress. But their numerical advantage is slim, and it would only take a few Republican defectors to potentially block the move.

What is the potential impact?

“Catastrophic”, “disastrous”, “damaging” is how some global public health experts are describing it.

Of the 196 member states, the US is by far the largest individual funder, contributing almost a fifth of the total WHO budget.

It’s possible that funding could disappear almost overnight and that could have an impact on the ability of the WHO to respond to emergencies.

There is also concern among some scientists that this would leave the US isolated when it comes to access to programmes such as pandemic preparedness and seasonal influenza strain sequencing, which is used to develop annual flu jabs.

That could ultimately harm the health of Americans, and the US national interest.

Some argue US withdrawal could prompt further reforms of how the WHO works, making it a body that better serves the public health needs of people around the globe.