Donald Trump’s former ghostwriter Tony Schwartz has dissected the president’s attack on the father of a college basketball player.

On Wednesday, the co-author of Trump’s 1987 book The Art of The Deal told CNN’s John Berman that POTUS’ feud with LaVar Ball stemmed from his perception of black people and his standard reaction to being under threat.

Trump recently traded insults with Ball, whose son LiAngelo Ball was one of the three UCLA basketball players detained in China earlier this month on shoplifting charges. Trump took credit for the trio’s release, but Ball dismissed his involvement.

Berman asked whether Trump’s attack was down to “what LaVar Ball said or, as some are alleging, how he looks.”

“Both,” replied Schwartz. “So first of all, [LaVar Ball] is a tall black man, and I think Trump is half awed and half frightened by black people, and his only way of dealing with them is to attack them.”

“On the other hand, I think he has a zero tolerance for any criticism of any kind, that’s why he goes after anybody who says virtually anything about him that’s negative,” he added.

Biographer Michael D’Antonio, who wrote The Truth About Trump, agreed with Schwartz’s analysis.

“I think what Tony said was correct, that there are these dual motivations on his part,” he said. “On the one hand, it is racial; on the other hand, he has very thin skin.”

Check out the full interview in the clip above.