"Libel laws are very weak in this country".
Wolff told BBC Radio in an interview broadcast on Saturday that based on his interviews with the people around Trump that he believed the president was unfit for office. "It's all about him", Wolff said.
The tweets were another sign of Trump's frustration at what he views as unfair treatment by the news media amid a federal investigation into whether he or his campaign aides colluded with Russian Federation during the 2016 presidential campaign, in which he defeated Democrat Hillary Clinton.
The US President boasted at a meeting at Camp David that he made "billions and billions of dollars" and became "one of the top business people" when questioned about the tweets.
Bannon infuriated Trump with comments to author Michael Wolff describing a June 2016 meeting at Trump Tower in NY between Donald Trump Jr., Trump campaign aides and a Russian lawyer as "treasonous" and "unpatriotic".
So he is easy pickings for someone like Michael Wolff, author of "Fire and Fury: Inside the Trump White House", which paints a frightful picture of Trump as an undisciplined, tempestuous, incompetent president. I am the only person to date to conduct a global effort to preach the message of Trump and Trumpism; and remain ready to stand in the breech for this president's efforts to make America great again.
"I literally think you go in there and say, 'I'm writing a book, ' and they go, 'Oh".
Eager readers are already able to buy the e-book version of Fire and Fury: Inside the Trump White House, but bookstores won't have physical copies until later in the week.
Soon after, Trump tweeted: "Jake Tapper of Fake News CNN just got destroyed in his interview with Stephen Miller of the Trump Administration". Sessions had not been invited to the weekend retreat.
Wolff told NBC News on Friday that White House staff treated Trump like a child. "And what they mean by that, he has a need for immediate gratification".
Even before the book, mental health professionals, Democrats and even some Republican legislators raised concerns about Trump. The exam was announced on December 7 after questions arose about Trump's health when he slurred part of a speech announcing that the United States recognized Jerusalem as the capital of Israel.
Trump has slammed it as "phoney" and called Wolff "a loser".
White House spokeswoman Sarah Huckabee Sanders this week called such suggestions "disgraceful and laughable".