"It's obviously been very rough", he said of the emotional toll the investigation has taken.
It appeared to be another instance of the president versus the administration, as Trump proceeded on one track while the agencies largely moved on another.
The publisher of Bob Woodward's book Fear is expecting one of the biggest publishing success stories of the year, printing one million copies to keep up with reader demand.
The denials from the Pentagon followed Woodward's appearance on NBC's Today Show Monday in which he said that Mattis, a retired Marine general, and retired Marine Gen. John Kelly, the White House Chief of Staff, were "not telling the truth" in rejecting how they were quoted in the book.
"These are political statements to protect their jobs - totally understandable", Woodward said.
White House press secretary Sarah Sanders said on Monday that the anonymous author of the New York Times op-ed that is searingly critical of Donald Trump's ability to be president, is "attempting to undermine the executive branch", and added that the US Department of Justice should "look into" the writer's identity.
UEFA to introduce third club competition
In a statement, Uefa said it is "constantly reviewing the format of its competitions and is looking at a variety of options". It was an idea first put forward in 2015 and should offer more chances for Scottish clubs to progress in European football.
"People who are well respected in this administration have come out and denied it", he said. That anonymous Times op-ed writer claims to be part of an inside "resistance", whose mission is to protect the country by neutralizing Trump's potentially unsafe impulses.
"And, that's how you end the book". Mattis then allegedly turned to an aide and said he would ignore Trump's demand. "It gives a time, who participated".
Set for public release Tuesday, "Fear" has thrown an already chaotic White House into disarray.
"I think there are people in there that he can trust, it's just - it's a much smaller group than I would like it to be", Trump Jr., 40, said on ABC's "Good Morning America." Many senior aides have also scrambled to deny they made the comments, claiming they weren't quoted accurately by the investigative reporter. Dems can't stand losing. Some officials, the author wrote, had discussed the 25th amendment, which can be invoked to remove a president from office if the vice president and cabinet declare he or she is unfit to hold the office.
Deutsche Bank was under investigation by the Justice Department for both its role in a " mirror trading " scheme with Russian oligarchs that allowed them to launder cash out of Russia in the face of United States sanctions, and for its mortgage practices amid the financial crisis, which regulators sought a $14 billion fine for.