Bob Woodward reveals what shocked him most in new Trump book

Donald Trump's presidency has been rocked by a series of damning revelations including a scathing opinion piece by an unnamed senior administration official who described a

Woodward's much-awaited book, "Fear: Trump in the White House", shows aides routinely ignoring or acting to block orders by the U.S. president.

"He says these are all unnamed sources, but these are not unnamed instances", Woodward said on NBC.

"Some of the things Trump did, and does, jeopardize the real national security", Woodward said.

More: Bob Woodward on Donald Trump and "Fear": Is it time to feel afraid?

In another part of the book, Mattis allegedly said that Trump had the understanding of a "fifth- or sixth-grader" of the situation on the Korean peninsula.

Porter said he was "struck by the selective and often misleading portrait it paints of the president and his administration".

Trump and several members of his administration were quoted have called the book "fiction and fabrication". "So I think it's - in a sense - the wrong phrase".

Woodward in the book recounts how Defense Secretary James Mattis had to explain to Trump why the United States pays $3.5 billion a year to station 28,000 troops in South Korea, telling the president it was a key line of defense against North Korea to prevent "World War Three". Since excerpts were released last week, Trump has accused Woodward of making up quotes attributed to him and others. "It's a way of saying, 'You're important to this story, I take you seriously, '" he said. Instead, Sanders said just the notion the unidentified official may be involved in national security matters was grounds enough to launch a probe.

"This is a very low-level person who will throw their name on an op-ed, and basically subvert the vote of the American people who elected my father to do this job", Trump Jr. said, calling the editorial "pretty disgusting" and "sad".

The book has caused controversy as it reportedly portrays Trump as chaotic, mercurial and uninformed.

The Washington Post editor and author of Fear: Trump in the White House recounted an incident in which the president complained about USA troops in the Korean peninsula.

"We have reprinted six times for a total of seven to meet extraordinary demand - that will put one million books in print before we've even gone on sale", a Simon & Schuster spokesperson told CNN. Dems can't stand losing. Trump tweeted Monday prior to the Woodward interview. Trump himself has shown little willingness to let Woodward's claims go by the wayside, tweeting the famed Watergate journalist "is a liar who is like a Dem operative prior to the midterms".

"The working dinner was at the White House", Woodward, the famed investigative journalist, writes in the book.