In the terminal phase of Richard Nixon’s presidency, in the American summer of 1974, defence secretary James Schlesinger worried that Nixon’s mental decline would lead to a nuclear incident. By this point, secretary of state Henry Kissinger had labelled Nixon, who was drinking heavily, the “meatball president”. Consequently, Schlesinger instructed the military that no orders issued from the White House related to the US’s nuclear capability should be acted on without checking with the secretary of defence or the secretary of state.

In the light of the presidential behaviour expose­d by Bob Woodward in his exceptional new book, Fear: Trump in the White House, Defen­ce Secretary Jim Mattis would do well to ­remember Schlesinger’s unconstitutional but effective precedent. This is particularly relevant in the case of the Korean peninsula, but more on that later.

Woodward made his reputation alongside Carl Bernstein as the dogged and insightful Washington Post journalists pursued the Watergate burglary until it unravelled into a scandal of such proportions that the Nixon White House collapsed. Their two books on the period, All the President’s Men and The Final Days, are justifiably regarded as political classics.

Now, after 17 further books and two Pulitzer prizes, Woodward has become the journalistic version of the Smithsonian Institution: he holds a significant store of knowledge on the American republic. He writes about power and those who wield it. He does not disappoint in this new book.

Meanwhile, Ben Rhodes, who became Barac­k Obama’s deputy national security adviser after an accomplished period as a speechwriter, has written a White House memoir that is the most engaging of this genre since Peggy Noonan published her account of Ronald Reagan’s presidency, What I Saw at the Revolution.

Where Woodward has interviewed dozens of Trump staff and former staff members for his book, Rhodes has written The World as It Is from the perspective of a campaign volunteer who was taken on to the candidate’s staff for his writing and foreign policy skills, and travelled with Obama from the Brandenburg Gate in Berlin to his final presidential commitment, an Asia-Pacific Economic Co-operation forum summit in Lima.

Along the way he writes for Obama on the night of Osama bin Laden’s death; he negotiates with the Castro dynasty in Cuba for a renewal of diplomatic ties; and he becomes a target for right-wing trolls who misrepresent a single email on Benghazi.

Woodward appears to have spoken off the record to several of the people who contributed to Michael Wolff’s tabloid expose of the Trump administration, Fire and Fury. Prominent among these seems to be Steve Bannon, once a close adviser and ideological kindred spirit to Donald Trump, now a true outsider, having lost his base at Breitbart News and his wealthy supporter­s in the Mercer family.

Bannon’s presence is significant in Fear. In these pages he supports the President in his determina­tion to roll back the globalist agenda favoured by advisers such as Gary Cohn (directo­r of the National Economic Council), Rex Tillerson (secretary of state), Mattis and HR McMaster (national security adviser). Three of these senior advisers are already gone and Mattis is unlikely to survive long-term.

Trump’s withdrawal of US membership of multilateral treaties such as the Paris Agreement and the Trans-Pacific Partnership is well known, as is his repudiation of Obama’s nuclear treaty with Iran. What is not widely known is more disturbing for US allies.

Woodward records that Trump sought unilaterally to discard the US alliance with South Korea. He was enraged by an $US18 billion trade deficit with the ally and was determined to destroy the trade relationship. Worse, ignoring the value of the alliance, particularly in relation to early warning of a nuclear attack, Trump pushed repeatedly to end security ties with Seoul. Woodward writes all this came to a head on January 19 this year at a National Security Council meeting in the Situation Room.

Trump had been informed about the edge the Special Access Program intelligence operations gave the United States in detecting a North Korea missile launch — seven seconds versus 15 minutes from Alaska. There was also an offensive cyber attack capability. It had mixed results sabotaging North Korean missiles before or after launch.

Mattis showed signs that he was tired of the disparaging of the military and intelligence capability. And of Trump’s unwillingness to comprehend their significance.

“We’re doing this in order to prevent World War III,” Mattis said. He was calm but stark. It was a breathtaking statement, a challenge to the President, suggesting he was risking nuclear war.

Typically, at these meetings to discuss importan­t policy questions, Trump insults his advisers, berates his generals and dismisses alter­native views with a curt “I don’t want to hear this”. Consider what a rupture in the US-South Korea relationship would have meant. Kim Jong-un would have been emboldened and greater aggression by Pyongyang almost certain. The US-Japan security treaty, the bedrock for international stability in North Asia, would have been shaken to its foundations. China would have increased pressure on Taiwan and the Association of Southeast Asian Nations, and every US ally would have had to question Washington’s willingness to abide by its treaty obligations. This would have applied equally to NATO, the Middle East and the Asia-Pacific.

The toughest national security decision of Obama’s presidency was the raid by US Navy SEALs on Abbottabad in Pakistan in 2011. The intelligence on bin Laden’s whereabouts pointed to a villa not far from Pakistan’s main military academy, but it was inconclusive. The target was described as “the pacer”, a figure who walked in the courtyard of a house behind a high wall; comings and goings were rare, and the household burned all its trash.

Obama weighed the options and sought frank advice from senior aides. Defence ­secretary Robert Gates and vice-president Joe Biden were opposed. Secretary of state Hillary Clinton and CIA director Leon Panetta were firmly in favour. Rhodes writes:

It was obvious to me that Obama was going to do this. He had a way of looking straight ahead when he was listening at the same time that his mind was elsewhere. I could tell that he had turned the intelligence over and over in his mind (“this is a fifty-fifty call”), that he understood the risks with Pakistan. When he asked me what I thought, I simply said, “You were always going to do this.”

And so he did, in a carefully calibrated exercise of presidential power.

The US presidency is often described as the most powerful elected office in the world. This is true only to a certain extent, and it was never meant to be this way. The framers of the US constitution were driven by an overwhelming determination that the infant American republic would never be threatened by another ­George III, domestically or externally.

To this end, the powers of the presidency were limited and defined, with real power intend­ed to be reposed in congress. The Suprem­e Court began to assume the role of the third tier of government only when it insisted on a power of constitutional review, beginning with Marbury v Madison (1803).

However, the power to act as commander-in-chief of the US military was afforded the president, and that is decisive. Abraham Lincoln confirmed this power during the civil war and by the time of Franklin D. Roosevelt and World War II this power was beyond doubt. It is now reflected in the US military attache who accompanies the president everywhere with “the football”, a bag containing the US nuclear codes.

Obama’s critics have often sneered at the 44th president as feckless or feeble. But he was determined to take the US out of wars in the Middle East and to rely on the tools of diplo­macy rather than the arsenals of the Pentagon.

This leads Rhodes to negotiations in Canada with Raul Castro’s son Alejandro Castro Espin on diplomatic recognition. The talks succeed and Rhodes finds himself in Havana opposite Raul Castro in the days after Trump’s election:

I tried to reassure Raul that he should seek a deal with Trump, that the forces in the United States still pointed — inevitably — toward engagement between our countries. As I talked, I thought about how he was into his eighties, that this change he had initiated with the United States might not fully take hold during his lifetime after all. He smiled, driving his eyes to squint. “Ben,” he said. “There was once a general from Ossetia who had the authority to launch nuclear missiles from my territory without telling me, even though I was defense minister. I’ve dealt with harder things than Trump.”

Cuban dictators aside, the people who appea­r to have the most problems with Trump throughout Woodward’s book are close presidential aides, who are routinely abused, derided or dismissed.

Former chief of staff Reince Priebus, eventually to be sacked via Twitter, is described as “a little rat who just scurries around”; Commerce Secretary Wilbur Ross is told he is “over the hill”; but a special presidential venom is ­reserved for Rudy Giuliani, who appears on five US television networks one Sunday morning, doing “a full Ginsburg” (named for Monica ­Lewinsky’s lawyer), to defend the Republican candidate in the last month of the 2016 ­campaign. He barely makes the campaign plane. Once seated next to Trump, he is informe­d that he “is weak and has lost it”.

The President’s aides respond in two ways. Trump is variously characterised as a “moron” or an “idiot”, or presidential business is delayed or dislocated through the removal of documents from the presidential desk, built from the timbers of HMS Resolute, through to the exploitation of the notoriously short Trump attention span by deferring meetings and decisions.

As Obama observed recently, this is not the way the US system is supposed to work.

Casting a deep and lengthening shadow over the Trump administration is special counsel Robert Mueller.

Trump rages against the investigative light. Woodward is not entirely unsympathetic to his predicament. Clearly, Woodward has talked at length to Trump’s former defence attorney John Dowd, whose conclusion on the President is embraced by the author.

The most compelling conclusion, however, about Trump may well be drawn from a presidential annotation on a speech that reads: “Trade is bad.”

As Woodward observes: “Though he never said it in a speech, he had ­finally found the summarising phrase and truest expression of his protectionism, isolationism and fervent American nationalism.”