Can you believe that Trump has just tweeted this comment? He is talking about the protests about George Floyd's death. He has also called the protestors "thugs".
Twitter has put a warning on his twitter post, saying that it "glorifies violence". It is also racist!
The "historical context" is a reference to the late 1960s, when the phrase "when the looting starts, the shooting starts" was coined by Miami Police Chief Walter Headley, in reference to his aggressive policing policies in black neighbourhoods.