Ooh, that’s a big one,” Donald Trump said Monday as he signed an executive order – one of dozens during his first hours as president – to withdraw the United States from the World Health Organization.

The WHO is a United Nations agency that aims to expand universal health coverage, coordinates responses to health emergencies such as pandemics, and has a broad focus on healthy lives. It does not have the power to enforce health policy, but influences policy worldwide, especially in low-income countries.