U.S. President Donald Trump used one of the flurry of executive actions that he issued on his first day back in the White House to begin the process of withdrawing the U.S. from the World Health Organization for the second time in less than five years — a move many scientists fear could roll back decadeslong gains made in

The U.S. has traditionally been the most generous benefactor of the WHO. A Trump executive order to cut ties with the WHO could pose a threat to global public health.