Trump’s indiscipline was also a constant source of frustration. One day in February 2019, when congressional leaders were waiting for an answer from the White House on a pending deal to avoid a second government shutdown, the president demanded a DHS phone briefing to discuss the color of the wall. He was particularly interested in the merits of using spray paint and how the steel structure should be coated. Episodes like this occurred almost weekly.

The decision-making process was itself broken: Trump would abruptly endorse policy proposals with little or no consideration, by him or his advisers, of possible knock-on effects. That was the case in 2018 when then-Attorney General Jeff Sessions announced, at the White House’s urging, a “zero tolerance” policy to prosecute anyone who crossed the border illegally. The agencies involved were unprepared to implement the policy, causing a disastrous backlog of detentions that ultimately left migrant parents and their children separated.

Incredibly, after this ill-conceived operation was rightfully halted, in the following months the president repeatedly exhorted DHS officials to restart it and to implement a more deliberate policy of pulling migrant families apart en masse, so that adults would be deterred from coming to the border for fear of losing their children. The president was visibly furious on multiple occasions when my boss, then-Homeland Security Secretary Kirstjen Nielsen, refused.