This afternoon, the Associated Press is reporting that United States officials have officially ordered all public health officers to cease working at the World Health Organization just days after President Donald Trump signed an executive order pulling the United States out of the World Health Organization.

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.

Public health experts say the United States’ departure could cripple the WHO’s operations or leave an opening for China to assume greater control over the agency.

The World Health Organization is shaped by its members: 194 countries that set health priorities and make agreements about how to share critical data, treatments, and vaccines during international emergencies.