Bolton is a peculiar and stubborn man – you can tell that from his moustache. He’s also a greedy hack. Earlier this year, when all his old neocon NeverTrump allies were begging for him to testify in the president’s impeachment trial, he decided to stay quiet. He wanted to keep his powder dry for his tell-all book, no doubt in some small part because he was offered a $2 million (£1.6m) advance from publishers Simon & Schuster. If he cared even half as much as he claims to about America’s national interest, maybe he’d have acted differently.

Bolton’s new book is certainly newsworthy. The bombshells go bang. Trump’s extraordinary and fawning overtures to Chinese president Xi Jinping are, if true, particularly embarrassing for the president ahead of an election that will involve two candidates seeking to portray the other as weak on China. The revelation that Trump thought it was ‘cool’ to invade Venezuela is juicy, as is the claim that Secretary of State Mike Pompeo told Bolton that Trump was ‘full of shit’, especially since Pompeo and Bolton are old friends. What was Bolton’s agenda there, I wonder, beyond spite?

Simon & Shuster will certainly be feeling they made a good investment today – it’s making media waves and the Trump administration’s legal attempt to block publication will only add to its appeal. Readers might be a little disappointed, however – the book is 592-pages long and ponderous. Bolton, the narrator, emerges as quite a tiresome self-righteous bore. But then most people knew that already.

What Bolton’s memoir does reveal is the limits of president Trump’s improvisational and transactional approach to foreign policy. Trump is winging everything all the time, as most keen observers have been able to tell. He may, at some mysterious level, be playing three-dimensional chess on the world stage, but he is conspicuously ignorant on important subjects. According to Bolton, he didn’t even know Britain was a nuclear power.

‘I have two groups of people,’ said president Donald Trump last year. ‘I have doves and I have hawks. John Bolton is absolutely a hawk. If it was up to him, he’d take on the whole world at one time, ok? But that doesn’t matter, because I want both sides.’

President Donald Trump regards himself as America’s CEO in world affairs. In his head, he’s isn’t a hawk or a dove – he’s the big bald eagle who sits atop the greatest military power in the universe and calls the shots. Trump listens to pitches from advisers with different or opposing perspectives, then makes an executive decision, or doesn’t. This approach has its merits: it helps explain why Trump hasn’t got sucked into disastrous wars as his predecessors have done. As we’ve seen with North Korea, to Europe, to China, to Iran, Trump’s modus operandi is to be flexible. It also creates a usefully unpredictable will-he-won’t-he dynamic in his approached to all foreign problems – from North Korea to China to Venezuela and Iran.

But it also means that his advisers can feel spurned, angry, and vengeful. John Bolton is all that and more – though no doubt that $2 million in his bank account will help calm his temper.