WHO’s constitution, drafted in New York, doesn’t have a clear exit method for member states. A joint resolution by Congress in 1948 outlined that the U.S. can withdraw with one year's notice. This is contingent, however, on ensuring that its financial obligations to WHO “shall be met in full for the organization’s current fiscal year.”

The exit will cut a huge chunk from the World Health Organization’s budget, but the short-term financial gain for the US could come at the cost of disease outbreaks flaring up across the world.