Donald Trump must soon decide what to do about another potentially troublesome book by another national security adviser with whom he often clashed: HR McMaster, who at times offered stances at odds with his former boss.

The US president ousted McMaster in March 2018 after the duo failed to ever develop much of a rapport, with Mr Trump often mocking or refusing to meet with his top national security aide. New York-based Harper Collins will publish Mr McMaster's book in April – though it must first pass through a White House security review, just like all such works by former officials under any president.

Mr Trump's team is currently reviewing another book by another former national security adviser, John Bolton, with the conservative hawk promising its fourteenth chapter will contain some fiery details about the Trump team's Ukraine policy push, which became the basis of House Democrats' impeachment of the president.

Mr McMaster, a retired US Army one-star general, has remained mostly silent about his time working for Mr Trump, as well as the president's national security and foreign policy moves and remarks. But the book will give him a chance to tell his side of his steadily devolving relationship with the commander in chief.

"If you look at his first book, Dereliction of Duty, about the Vietnam War, he didn't throw people under the bus," said retired Army Lt Col Daniel Davis, who served under Mr McMaster in the 1990s Persian Gulf War. "That was really a history book about what happened and what went wrong. I think we'll see something very similar to that."

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"All indications are he will use this to push his views on foreign policy – which certainly did differ from the president's – and grand strategy," Mr Davis said. "There has been talk that the president still calls him to get his advice. I would expect McMaster to be very, very measured with any criticisms of the president."

As a career Army officer, Mr McMaster could opt to hold some fire. That's because he in the past has stated his belief in the military's ethos of respecting one's commander. Still, he also has said he always offered his candid advice to Mr Trump, even when the two sharply disagreed.

One example was Mr Trump's stunning decision to meet one-on-one with North Korean leader Kim Jong Un at a high-stakes summit in 2018 to discuss the country's nuclear weapons program.

"I wasn't really opposed to the summit. I had concerns that I raised with colleagues and with the president," Mr McMaster said shortly after the leaving the White House at an interview with the Hudson Institute, a think tank where he now runs the Japan program. "My concern was that the campaign of maximum pressure may not have proceeded long enough to really convince Kim Jong Un that his regime is less safe with nuclear weapons than he is without them."

During his stint as Mr Trump's second national security adviser, Mr McMaster at times was not shy about expressing views in public that ran counter to those of the president.

The book cover for Battlegrounds by HR McMaster, which is due to be published in April 2020 (AP)

For instance, the three-star Army general went to the Munich Security Conference in February 2018 and said plainly he saw "incontrovertible" evidence Russia meddled in the 2016 US presidential election.

In siding with all 16 American intelligence agencies and the Senate Intelligence Committee, Mr McMaster went much further than his boss. Trump has vacillated between refusing to pin the interference on Moscow and saying Russians likely were involved.

Russia was likely the one issue, at least in public, where the duo frequently delivered different messages.

Just before he left the White House, Mr McMaster delivered public remarks that were tough on Russia.

"For too long, some nations have looked the other way in the face of these threats. Russia brazenly and implausibly denies its actions, and we have failed to impose sufficient costs," he said during a speech at an Atlantic Council dinner. "Mr. Putin may believe that he is winning in this new form of warfare. Perhaps he believes that our free nations are weak and will not respond to his provocations. He is wrong."

But Trump, in stark contrast, rarely says a critical word in public about Russia or its president, Vladimir Putin.

"They don't think about the country. They don't think about jobs. They don't think about lowering your drug costs. Infrastructure. These people are crazy," Mr Trump said Friday during a campaign rally in Las Vegas, referring to congressional Democrats. "Trust me. I like ... what we're doing, and I love this country. I love this country. Now, and I campaigned on it, at the same time we want to get along with Russia. We want to get along with China."

"We want to get along with all these countries. Who the hell needs to have conflict?" he added, revealing his dovish side on global affairs that is a departure from his otherwise hardline and tough-talking demeanor.

Just how deep into such policy spats and their personal rows Mr McMaster ultimately decides to go is unclear.

But Harper Collins has signaled the work's main focus will be an academic "reassessment of America's place in the world, drawing from McMaster's long engagement with these issues, including 34 years of service in the US Army with multiple tours of duty in battlegrounds overseas." However, the firm also said the book will cover his time working for the former reality television host and New York real estate developer.

To be sure, he and the president had a rocky relationship.

By late 2017, there were multiple media reports that Mr Trump had lost confidence in Mr McMaster's advice.

In their book about the Trump White House, A Very Stable Genius, Washington Post reporters Carol Leoning and Phil Rucker report Mr Trump griped that the military man dressed "like a beer salesman." He also mocked and imitated Mr McMaster's "barking kind of voice" and military presence.