WASHINGTON (BLOOMBERG) - Mr Donald Trump put his re-election ahead of US national security, Mr John Bolton said in an interview with ABC News, calling the president disinterested in intelligence briefings and ignorant of global affairs and the impact of his decisions.

"My experience was he very rarely read much," Mr Bolton, Mr Trump's former national security adviser, told ABC's Martha Raddatz in advance of the publication on Tuesday (June 23) of his book The Room Where It Happened: A White House Memoir.

"Intelligence briefings took place perhaps once or twice a week," Mr Bolton said. "They should take place every day."

Mr Trump's "attention span was infinite" for his re-election, Mr Bolton said.

"It's just too bad there wasn't more of that when it came to national security."

Mr Bolton, 71, is on a media blitz to promote his tell-all book, one of the most damaging accounts yet of Mr Trump's White House. He is the highest-ranking administration official to publish a book after departing. He told ABC that the 2020 election was the last "guardrail" to protect the country from Mr Trump.

The Trump administration sought to block the publication of Mr Bolton's book, arguing that it contained sensitive information related to national security. At the same time, the president has said the book's allegations about him are "lies".

On Saturday, a judge rejected a last-ditch effort by the Justice Department to block publication. The book is scheduled to go on sale on Tuesday - one of a string of developments to complicate the president's re-election effort amid slumping poll numbers, the virus-ravaged economy and a renewed national debate over policing and racism.

Mr Trump has attacked Mr Bolton personally, calling him a "wacko" and "washed up". Mr Trump also said that Mr Bolton would have "bombs dropped on him" for proceeding with the publication of the book.

ABC earlier released excerpts of the interview in which Mr Bolton said that he didn't think Mr Trump was fit for office.

"I don't think he has the competence to carry out the job," Mr Bolton told ABC of Mr Trump. "There really isn't any guiding principle that I was able to discern, other than what's good for Donald Trump's re-election."

He said he wouldn't vote for either Mr Trump or his presumptive Democratic opponent, former vice president Joe Biden, in November.

"I'm gonna figure out a conservative Republican to write in," he said.

Mr Bolton called Mr Trump's son-in-law and senior adviser, Mr Jared Kushner, the most powerful person in the White House after the president. But he declined to say whether he believed Mr Kushner was qualified to oversee a broad portfolio that includes Mr Trump's re-election campaign and Middle East peace, saying "the focus ought to be on the president".

In the interview, he was severely critical of Mr Trump's diplomacy with North Korea. He called it "folly" for Mr Trump to cancel US war games with South Korea as a concession to North Korean leader Kim Jong Un. He described Mr Trump as obsessed with the number of reporters who would attend a news conference concluding his first summit with Mr Kim in Singapore.

"That's what he was focused on," Mr Bolton said. "That he had had this enormous photo opportunity - first time an American president has met with the leader of North Korea."

Mr Bolton said he considered the summit a "strategic mistake" and that the US "got nothing from that. Donald Trump got a lot".

In another advance clip released last week Mr Bolton said that Russian President Vladimir Putin can play Mr Trump "like a fiddle". The Kremlin on Friday rejected that characterisation.

"I think Putin is smart, tough," Mr Bolton says. "I think he sees that he's not faced with a serious adversary here. I don't think he's worried about Donald Trump."

Mr Bolton said he was appalled at Mr Trump's news conference with Putin after a Helsinki summit in July 2018, when the US president sided with the Russian leader in challenging American intelligence agencies' conclusion that the Kremlin interfered in the 2016 election.

"I thought I wouldn't get up. I didn't know what to do" after the news conference, Mr Bolton said. "I thought Dan Coats, then the director of national intelligence, was close to resignation."

'PARTISAN PLAY'

Mr Bolton defended his decision to publish a book instead of testifying in the House impeachment inquiry of Mr Trump's Ukraine scandal. He said he "didn't think the Democrats had the wit or the political understanding or the reach to change what, for them, was an exercise in arousing their own base, so that they could say, 'we impeached Donald Trump'."

"This was a partisan play," he said. "It was not a Constitutional process. I judge that to be almost as irregular as what they were accusing Trump of doing."

US District Judge Royce Lamberth faulted Mr Bolton for going ahead with the book before the pre-publication review process could be completed, writing that Mr Bolton "has exposed his country to harm and himself to civil (and potentially criminal) liability".

Mr Lamberth also signalled that Mr Bolton could lose in the next phase of the breach of contract lawsuit and may have to turn over a US$2 million (S$2.8 million) book advance and any royalties he receives from book sales to the government.

Mr Bolton's book paints an unflattering portrait of the White House, describing Mr Trump as ignorant of basic foreign policy facts and motivated largely by political self-interest. In one passage widely reported passage, Mr Bolton wrote that Mr Trump urged Chinese President Xi Jinping to buy agricultural products from the US because it would help the Trump campaign build political support in rural states.

Mr Bolton's account joins recent critical portraits of Mr Trump's character and fitness for office from other prominent national security officials, including former secretary of defence James Mattis, who gave a statement to the Atlantic alleging that three years under Mr Trump have eroded the foundations of American democracy.

"Donald Trump is the first president in my lifetime who does not try to unite the American people - does not even pretend to try," Mr Mattis wrote. "Instead he tries to divide us. We are witnessing the consequences of three years of this deliberate effort. We are witnessing the consequences of three years without mature leadership."

And in October, Admiral William McRaven, the former commander of America's special operations forces, penned an Op-Ed for the New York Times alleging that Mr Trump was a threat to the republic and that it was time for new leadership in the Oval Office.