For three weeks, John Bolton had kept his counsel. After leaks from his manuscript sent shock waves through President Trump’s impeachment trial and reignited demands that witnesses be called to give evidence, the man who had so far declined to give testimony was about to speak.

“I’m so pleased that Duke has been able to do what neither the House nor the Senate was able,” said his host Peter Feaver, professor of political science, his words drowned out by a mix of groans, laughs, and applause from the capacity audience in the Duke University auditorium.