In our experience, a President must be willing to listen to his advisers and department heads; must encourage consideration of conflicting views; and must acknowledge errors and learn from them. A President must be disciplined, control emotions, and act only after reflection and careful deliberation. A President must maintain cordial relationships with leaders of countries of different backgrounds and must have their respect and trust. In our judgment, Mr. Trump has none of these critical qualities. He is unable or unwilling to separate truth from falsehood. He does not encourage conflicting views. He lacks self-control and acts impetuously. He cannot tolerate personal criticism. He has alarmed our closest allies with his erratic behavior. All of these are dangerous qualities in an individual who aspires to be President and Commander in-Chief, with command of the U.S. nuclear arsenal.