Just days earlier, K.T. McFarland, the deputy national security adviser, had given Trump a printout of two Time magazine covers. One, supposedly from the 1970s, warned of a coming ice age; the other, from 2008, about surviving global warming, according to four White House officials familiar with the matter.

Trump quickly got lathered up about the media’s hypocrisy. But there was a problem. The 1970s cover was fake, part of an Internet hoax that’s circulated for years. Staff chased down the truth and intervened before Trump tweeted or talked publicly about it…

That is what happened in late February when someone mischievously gave the president a printed copy of an article from GotNews.com, the website of Internet provocateur Charles C. Johnson, which accused deputy chief of staff Katie Walsh of being “the source behind a bunch of leaks” in the White House.

No matter that Johnson had been permanently banned from Twitter for harassment or that he offered no concrete evidence or that he’s lobbed false accusations in the past and recanted them. Trump read the article and began asking staff about Walsh. Johnson told POLITICO that he tracks the IP addresses of visitors to his website and added: “I can tell you unequivocally that the story was shared all around the White House.”