President Donald Trump has said he is going to halt US funding to the World Health Organization (WHO) because it had "failed in its basic duty" in its response to the coronavirus outbreak. But what is the WHO and what does it do? It's the global health HQA wash of colour overhead greets anyone entering the WHO headquarters in Geneva where the 194 flags of the organisation's member states drape from the ceiling as - on sunny days, at least - beams of light flood the large open atrium. This is from where the global response to what's been described as "the greatest test to the world since World War Two"- is being co-ordinated. The UN agency was founded in 1948, and describes itself as the "global guardian of public health". Its stated goal is to ensure "the highest attainable level of health for all people". It's a big job. Over the last 11 years, it has overseen the global response to six international health emergencies, including the Ebola outbreak in west Africa in 2014, the Zika outbreak in 2016 and - right now - the Covid-19 pandemic.