Trump told his biographer that he “always felt that I was in the military” because of his time at New York Military Academy, a boarding school he had been sent to in his youth. He explained that he’d received “more training militarily than a lot of the guys that go into the military.”

While Trump received five draft deferments for Vietnam, he still explained that, “I felt that I was in the military in the true sense because I dealt with those people.” He has also told the same biographer that his temperament had not much changed since he was in the first grade.

The New York Times – Donald Trump Likens His Schooling to Military Service in Book
Business Insider – Donald Trump: ‘I always felt that I was in the military’ by attending a military school
Snopes – Donald Trump Compared Prep School to Military Service?