On his first day back in the White House, US President Donald Trump began the process of withdrawing the US from the World Health Organization (WHO). Trump had initiated the US pullout during his first term,

Experts have warned the US' withdrawal could seriously weaken the world's defences against diseases, as it would put a massive dent in the WHO's resources. So why does Donald Trump want to leave?

The move to exit the WHO is historic and controversial. The U.S. has long been the most generous provider of humanitarian assistance.