As soon as we sit down, General Mark Milley, the recently retired chairman of the US Joint Chiefs of Staff, wants to “establish boundaries” — something his daughter taught him was important. I explain that we will discuss geopolitics and security, but caution that our lunch could meander in odd ways. Given that Milley served as the top military adviser to President Donald Trump, he is no stranger to unorthodox moves.

In his 44 years in uniform, the four-star officer saw his share of action overseas. But the most tumultuous period of his career was in Washington when he served as chairman for the final 16 months of Trump’s presidency. 

One flashpoint came when Milley let himself become a prop in a political stunt that Trump pulled in June 2020. Dressed in military fatigues, he joined the president for the first part of an infamous walk to a church near the White House — a piece of theatre that Trump intended as a response to the Black Lives Matter protesters who had been forcibly dispersed from the area. Milley, who had been attending a meeting in the White House, says he thought he was accompanying Trump and then secretary of defence Mark Esper to see the National Guard troops and police near the White House.