NBC's "Commander in Chief Forum"
https://www.washingtonpost.com/news/the-fix/wp/2016/09/08/its-not-clear-that-donald-trump-understands-the-relationship-between-the-president-and-the-military/
"'I know more about ISIS than the generals do. Believe me,'" Lauer quoted Trump as saying, then asked: "Was that the truth?"
"Well, the generals under Barack Obama and Hillary Clinton have not been successful," Trump replied. "I think under the leadership of Barack Obama and Hillary Clinton, the generals have been reduced to rubble. They have been reduced to a point where it's embarrassing for our country."
"Have you lost faith in the military commanders?" Lauer pressed a bit later.
"I have great faith in the military. I have great faith in certain of the commanders, certainly," he said. "But I have no faith in Hillary Clinton or the leadership."
Trump offered that line about "different generals" casually, but it's not an insignificant claim. As president, Trump's ability to overhaul the leaders of the military is limited. As commander-in-chief, he can remove generals from positions but he "doesn't enjoy Donald Trump-like powers to summarily fire service members," as Brian Palmer explained