Pentagon Adviser Resigns, Says Esper Violated His Oath Of Office

James Miller resigned from the Defense Science Board, accusing Defense Secretary Mark Esper of violating his oath by supporting the use of force against protesters near the White House. This occurred before President Trump visited St. John's Episcopal Church with Esper and other officials. Miller criticized Esper for not opposing the forceful actions. Esper defended himself, stating he was unaware of the photo opportunity at the church. The Pentagon supported Esper's claim. Miller had joined the Defense Science Board in 2014, previously serving as Under Secretary of Defense for Policy.

What was Esper's explanation for his trip out of the White House on Monday?

What position did Miller hold before joining the Pentagon's Defense Science Board?