By the end of December, it was clear that privately urging Trump to do the right thing was fruitless. He didn’t care. I had had several firsthand experiences of sitting in the Oval Office, calmly trying to tell Donald Trump what he did not want to hear. I knew how he would respond. A private approach would not work. We needed a public warning to Trump, and to his new appointees at the Pentagon. And it needed to come from a leader or group of leaders who could not easily be ignored.

