John Bolton, the former US national security advisor, is making explosive allegations about President Donald Trump in a new memoir, "The Room Where It Happened."

Trump has denounced the book as "pure fiction" -- but his administration has sought to block it on the grounds that it contains classified information.

Here are some of the key claims in Bolton's book, as reported ahead of its publication by The New York Times, The Washington Post and The Wall Street Journal:

John Bolton, then national security advisor, listens to US President Donald Trump in an April 2018 meeting in the Cabinet Room
John Bolton, then national security advisor, listens to US President Donald Trump in an April 2018 meeting in the Cabinet Room GETTY IMAGES NORTH AMERICA / MARK WILSON

"I am hard-pressed to identify any significant Trump decision during my tenure that wasn't driven by re-election calculations," writes Bolton, who left his position in September.

Despite widespread disputes with China, Bolton said that Trump asked his counterpart Xi Jinping in a meeting to boost purchases of soybeans and wheat in an explicit bid to help his chances of winning a second term through support from farmers.

The episode has echoes of Trump's freeze on military aid as he pressed Ukraine's leader to dig up dirt on US domestic rival Joe Biden, a revelation that led to the president's impeachment by the House of Representatives.

Bolton, known for his hawkish views, says he was alarmed that Trump warmed up to autocratic leaders.

US President Donald Trump gestures next to China's President Xi Jinping during an event at the Great Hall of the People in Beijing in November 2017
US President Donald Trump gestures next to China's President Xi Jinping during an event at the Great Hall of the People in Beijing in November 2017 AFP / Nicolas ASFOURI

He writes that Xi explained to Trump why China has detained masses of Uighurs and other Turkic Muslims, in what US lawmakers charge may be a crime against humanity designed to destroy minority groups.

Trump, hearing Xi argue that the camps are meant to reduce Islamic radicalism, agreed that the camps were "exactly the right thing to do," Bolton writes.

"In my government experience, it was the most irrational thing I ever witnessed any president do," writes Bolton, 71, who has served under Republican presidents since Ronald Reagan.

Trump also appeared to envy the behavior of autocrats, once saying that journalists he dislikes should be executed as they are "scumbags."

US President Donald Trump and Turkey's president Recep Tayyip Erdogan may no longer see eye to eye
US President Donald Trump and Turkey's president Recep Tayyip Erdogan may no longer see eye to eye POOL / Dominique JACOVIDES

Bolton writes that Trump, who came from the worlds of real estate and show business, was inclined to offer "personal favors to dictators he liked."

Trump was said to be receptive to Turkish President Recep Tayyip Erdogan who brought up the criminal charges against one of his country's largest banks over violating US sanctions on Iran.

Trump told Erdogan that "he would take care of things," explaining that New York prosecutors handling the case were appointed by former president Barack Obama and can be replaced, Bolton writes.

Bolton, in line with previous reporting, writes that Trump appeared ignorant of basic facts about the world.

He writes that Trump asked whether Finland, where he met his Russian counterpart Vladimir Putin, was part of Russia and voiced surprise when a British official told him the US ally had a nuclear arsenal.

"Oh, are you a nuclear power?" Trump is quoted as saying, in what Bolton writes "was not intended as a joke."

Bolton writes that Trump also appeared fixated on trivial matters such as sending an Elton John CD to North Korean leader Kim Jong Un, whom he had mocked as "Little Rocket Man" before engaging in talks with him.

Bolton writes that he was not alone in his views and that Trump's aides widely disparaged him behind his back.

Even Secretary of State Mike Pompeo -- publicly a stalwart ally of Trump who traveled four times to North Korea in 2018 -- privately dismissed Trump and especially his outreach to Kim, according to Bolton.

Pompeo slipped a note to Bolton during Trump's historic first meeting with Kim in Singapore, saying of the president, "He is so full of shit," Bolton writes.

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