Trump allies say his attitude about foreign interference is rooted in a deep sensitivity about the notion that he won in 2016 because of Russian interference and thus his victory was not legitimate.

“That’s what drives him,” said one source close to the White House, who requested anonymity to discuss Trump’s thinking. “It ties into this false idea which he detests that he was elected because of it. It seems like that’s what causes him to be defensive about the Russia stuff.”

Trump also does not like to admit fault, and saying he would call the FBI if offered damaging information on a rival would represent a tacit concessions that his campaign should have done so when it received offers of dirt on Hillary Clinton from figures linked to the Russian government in 2016.

“This is what you get when you have a president who is unfiltered and giving you what he actually thinks,” the source close to the White House said.