(CNN) — Former White House national security adviser John Bolton called President Donald Trump “naive and dangerous,” in an ABC News interview that aired Sunday, adding that he hopes his former boss will be remembered as a one-term president.

The remarkable statement made by a former key adviser to the sitting US president comes after details of Bolton’s upcoming book, “The Room Where it Happened,” leaked this week despite the fact that it remains the focus of an ongoing legal dispute.

“I hope (history) will remember him as a one-term president who didn’t plunge the country irretrievably into a downward spiral we can’t recall from. We can get over one term — I have absolute confidence, even if it’s not the miracle of a conservative Republican being elected in November. Two terms, I’m more troubled about,” Bolton told ABC News’ Martha Raddatz.

Regarding the President, Bolton said, “I don’t think he’s fit for office. I don’t think he has the competence to carry out the job. I don’t think he’s a conservative Republican. I’m not gonna vote for him in November. Certainly not gonna vote for Joe Biden either. I’m gonna figure out a conservative Republican to write in.”

‘Naive and dangerous’

Bolton elaborated on many of the key themes outlined in his book, including Trump’s affinity for authoritarian leaders, including North Korean dictator Kim Jong Un, which the former national security adviser says has become more of a threat despite the President’s overtures.

“The idea that — just this oleaginous — layer of compliments to this brutal dictator would convince him that you could make a deal with Donald Trump, I thought, was both strikingly naïve and dangerous,” Bolton told ABC News.

“The threat from North Korea today is absolutely greater. Because while all these photo opportunities were taking place, there’s absolutely no doubt that North Korea’s work on both its nuclear and ballistic missile programs continued. It’s one of the most secretive societies on the planet,” he said.

Bolton, a hawk on North Korean policy, said he did not believe the regime has “slowed down one bit during these two years of negotiations. So like the eight years of Obama, we just lost another two or three years. And the North Korea and the Iranian and other rogue state capabilities continue to advance.”

Kim was also able to manipulate Trump, Bolton says in his book.

Bolton writes extensively about his disagreements with Trump’s approach to North Korea before, during, and after the Singapore summit with Kim, which Bolton hoped would “collapse” before it happened and compared to the appeasement of Nazi Germany, even quoting Winston Churchill.

“The whole diplomatic fandango was South Korea’s creation,” Bolton writes, “relating more to its ‘unification’ agenda than serious strategy on Kim’s part or ours.”

Despite the objections of his advisers, Bolton writes that “Trump was desperate to have the meeting at any price.”

Bolton then writes that Kim had Trump “hooked” at the Singapore summit as they flattered each other in their meeting.

When Trump told Kim he would seek Senate approval of any nuclear deal, Bolton writes Secretary of State Mike Pompeo passed Bolton a note saying “he is so full of shit.” Bolton suggests Pompeo was referring to Trump, not Kim.

And Trump’s interactions with Kim were not the only instances that raises concerns for Bolton who said he was surprised about how the President was eager to meet with Russian President Vladimir Putin and other autocrats.

“I think there was the same fascination with speaking with a leader like Putin that we saw with respect to Xi Jinping and Kim Jong Un. It was hard to explain. The President himself used to comment on how strange it was that in one trip he took to a NATO summit, a summit with Theresa May, the prime minister of Britain, and then Vladimir Putin in Helsinki that he thought the easiest, most pleasant one might be with Vladimir Putin.”

In his interview with ABC News, Bolton said he believes Putin thinks he can play Trump “like a fiddle.”

“I think Putin is smart, tough. I think he can see that he’s not faced with a serious adversary here. I don’t think he’s worried about Donald Trump,” Bolton said.

Trump has previously claimed that no other president has been tougher on Russia than he has but that claim has been questioned by several of his own advisers, in addition to Bolton.

In his new book, Bolton writes that he was worried about leaving Trump alone in a room alone with Putin during the 2018 Helsinki Summit.

“I didn’t know what he would say. At any given moment, we didn’t know what he was gonna say. Now, it turned out and I say in the book, I feel very confident nothing untoward happened in the one on one. But that means we escaped without injury in the meeting. That not advancing American interests. I mean, it’s better than sustaining the injury. But it’s certainly not advancing the interests,” he says.

The press conference in Helsinki, during which Trump, standing alongside Putin, declined to endorse the US government’s assessment that Russia interfered in the 2016 presidential election, was particularly shocking for Bolton and other top officials.

“I thought I wouldn’t get up. I didn’t know what to do … I thought Dan Coats, then the director of national intelligence, was close to resignation,” Bolton told ABC News.

Lingering impeachment questions

Bolton devotes his final chapter to the Ukraine matter, in which he was part of several key meetings, including some described by other witnesses during the impeachment proceedings. But Bolton leveled an accusation in the book that no impeachment witness did: that he directly heard Trump tie withholding US security aid to an investigation into the Bidens.

“The next morning, August 20, I took Trump’s temperature on the Ukraine security assistance, and he said he wasn’t in favor of sending them anything until all the Russia-investigation materials related to Clinton and Biden had been turned over,” Bolton writes.

The former national security adviser reiterated that claim during Sunday’s interview with ABC News

“There is no question in my mind that — the President felt that the prior Ukrainian government — had been part of a conspiracy to take him down. He said that on any number of occasions. And that what he wanted — from the Ukrainians — this took months to develop. It didn’t — it didn’t happen all at once,” he said.

Trump “wanted a probe of Joe Biden in exchange for delivering the security assistance that was part of the congressional legislation that had been passed several years before. So that in his mind, he was bargaining to get the investigation, using the resources of the federal government, which I found very disturbing,” Bolton added.

Still, the lingering question remains: If Bolton was so troubled by Trump’s actions, why didn’t he speak up, especially during the impeachment proceedings?

House Democrats wanted Bolton to testify last year, but he refused to do so, threatening a legal battle if he was subpoenaed. Bolton offered to testify during the Senate impeachment trial, but Republicans voted to reject hearing from any witnesses.

Bolton wrote that the Democrats’ conducted a hurried, partisan investigation, and accused them of committing “impeachment malpractice” by only focusing on Trump’s involvement with Ukraine.

Asked why he did not testify during impeachment during Sunday’s interview, Bolton said his testimony in impeachment proceedings would not have mattered.

“I don’t think it would have made a difference because of the way the Democrats pursued the impeachment process in the House,” he said.

“I was fully prepared — if I got a subpoena like everybody else who testified got a subpoena. I think the way the House advocates of impeachment proceeded was badly wrong. I think it was impeachment malpractice. I think they were determined because of their own political objectives to conduct an impeachment proceeding that was very narrowly focused on Ukraine, and that went very, very quickly,” Bolton added.

When asked if the President was lying when he tweeted that he never told Bolton that Ukraine aid hold was ever tied to Biden, Bolton said he was lying. “Yes he is. And it’s not the first time, either.”

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