During a live phone-in on Fox Business, Donald Trump complained again that not enough of his political enemies have been arrested – and said attorney general Bill Barr could find himself in “a sad situation” if he doesn’t start rounding them up.

The blunt warning comes after Mr Trump left Walter Reed Medical Centre and returned to Twitter with a blizzard of angry tweets and retweets, many of them calling for the indictment of Obama administration figures.

None of opaqueness should come as surprise, though. Few occasions of historical importance have been so shrouded in secrecy — and even outright deception — as the health emergencies of world leaders. The U.S. may have been more transparent about these events than most countries, but, even here, the truth has only come to light over time.