The Madman Doctrine of negotiation has never worked, and it won’t work for the Brexiteers either.

In April 1971, with peace talks with North Vietnam stalled, US president Richard Nixon told his national security advisor Henry Kissinger to suggest to North Vietnamese negotiators that Nixon “will stop at nothing”, implying that he might use nuclear weapons to end the Vietnam War.

“You can say ‘I cannot control him’, put it that way,” Nixon said.

Kissinger agreed: “Yeah, and imply that you might use nuclear weapons.”

Nixon then ordered Kissinger to tell Hanoi: “He will. I just want you to know he won’t cave.”

In his memoir The Ends of Power, Nixon’s Chief of Staff, H.R. Haldeman, wrote that Nixon had told him: “I call it the Madman Theory, Bob. I want the North Vietnamese to believe I’ve reached the point where I might do anything to stop the war.

“We’ll just slip the word to them that, ‘for God’s sake, you know Nixon is obsessed about communism. We can’t restrain him when he’s angry—and he has his hand on the nuclear button’, and Ho Chi Minh himself will be in Paris in two days begging for peace.”

Nixon was following the playbook of his mentor in foreign policy, John Foster Dulles, President Dwight D. Eisenhower’s secretary of state. Dulles was credited by some in Washington with ending the Korean War by suggesting to China that the former Allied commander was capable of using nuclear weapons to finish that conflict.

According to Nixon’s autobiography, Lyndon B. Johnson, then the Senate minority leader, told Nixon that he believed the Soviets “‘feared Ike’ because of what Dulles had threatened to do in Korea”.

It should be noted that while Eisenhower was far too serious a soldier to allow it be suggested that he was insane, Dulles did intimate to Indian prime minister Jawaharwal Nehru that Eisenhower might resort to nuclear weaponry to end the Korean conflict. It was Dulles’ expectation that this information would get back to Mao.

Eisenhower biographer William Hitchcock argues that “the Dulles ploy” is in truth a self-serving myth invented by Dulles after the fact, noting that evidence shows that – if the story even got to Beijing – it played no part in China’s decision-making.

If Nixon and Kissinger realised that Dulles was bigging himself up, they didn’t care, and Nixon added his own twist to “the Dulles ploy”, the suggestion that the US commander-in-chief wasn’t just a hard man, he was also unstable. Of course, given his mental health issues and his heavy drinking, and his erratic medication usage, Nixon really was unstable, but then he would hardly be the last powerful man given to unintended sincerity. In any case, the madman approach can hardly be judged as a success for Nixon, with the Vietnam War dragging on for three-and-a-half more years, and costing a further 21,000 American lives and untold Vietnamese casualties.

More recently, the current occupant of the Oval Office, perhaps the only US politician so ill-educated as to consider Nixon a role model, tried his own version of the Madman Doctrine on North Korea, goading Kim Jong-un as “Little Rocket Man”, threatening to rain down “fire and fury” on Pyongyang, and claiming that his nuclear button was bigger than Kim’s. In fairness, for a man with such tellingly tiny hands, Trump, like Nixon before him, always keeps his neuroses in plain sight.

Trump’s apologists would claim that his madman tactics paid off, to the effect that they actually brought Kim to the negotiating table in June 2018.

There are two problems with that narrative. The first is that Trump’s predecessors never sat down with North Korea not because North Korea was unwilling to negotiate, but because the US believed that to do so would grant legitimacy to the pariah state. Getting to the negotiating table was exactly what the Kim dynasty wanted, and Trump’s Nixon tribute act played right into Kim’s hands. The second is that since Trump’s alleged diplomatic triumph, North Korea has reverted to its default bellicose behaviour, lobbing out test missiles to beat the band and terrorising its neighbours. For all of Kim’s flattering Trump as “Your Excellency”, all Trump’s madman diplomacy achieved ultimately was to strengthen North Korea, while making the US look both impotent and incompetent.

Closer to home, Boris Johnson, somehow the UK prime minister – sitting atop an unassailable 80-seat-majority in a country which has fixed parliamentary terms – has now launched into his own version of madman diplomacy, putting forward draft legislation which would unilaterally modify parts of the Brexit withdrawal agreement, an internationally binding treaty which his own government negotiated with the EU in good faith last year.

“To be honest,” a weary Simon Coveney responded to news of Johnson’s bill last week, “nothing surprises me with Brexit negotiations.”

Johnson himself had hailed the treaty only last October, selling it to voters as “a great deal”, and seeing it ratified in parliament to cheers from his own Brexiteers. Now the British government’s Internal Markets bill will tear up the provisions of the withdrawal agreement covering state aid and post-Brexit trade between Northern Ireland and Great Britain, something which Northern Ireland Secretary Brandon Lewis told the House of Commons “does break international law in a very specific and limited way”.

Last week, Rory Montgomery, former Irish ambassador to the EU, noted that while Johnson may be adopting Trumpian madman tactics in shredding the deal he did with the EU last year, that deal only happened because Johnson ended up accepting 95 per cent of what his predecessor Theresa May had negotiated and “backpedaling on the other 5 per cent”.

Breaking international treaties is something which rogue nations do, and – as former British Labour Party leader Ed Miliband noted in the House of Commons on Monday, Johnson has managed to unite all five of his living predecessors as prime minister, Major, Blair, Browne, Cameron and May, in condemning Johnson’s trashing of the UK’s international reputation.

Boris Johnson was reported to have said in 2018: “If Donald Trump was negotiating Brexit, he would create chaos right at the start of negotiations.” It seems certain that the Internal Markets bill is a Dominic Cummings-inspired attempt at Trumpian madman diplomacy, but the endgame seems unclear, and it’s hard not to suspect that – beyond their successful election slogan “Get Brexit Done” – the Tories don’t actually have a Brexit strategy. At best everything is tactics, if that is even what they are. Boris Johnson is a lazy and particularly stupid man who has mastered a few Latin phrases, whose priapic pursuit of power has proven the same as all of his other romantic hunts, and upon the initial, unsatisfactory conquest, he has already lost interest.

Johnson is happy to outsource whatever thinking there is in Number Ten to Cummings, a petty, nihilistic narcissist who is convinced that he is being played by Benedict Cumberbatch in real life too, a man whose conviction that the rules don’t apply to him seems only to guarantee an almighty comeuppance somewhere likely not too far down the road.

Boris Johnson’s suggesting that the EU poses a threat to the unity of the UK is a nonsense, and claiming that the Internal Markets bill is designed to protect the Good Friday Agreement is a barefaced lie.

Despite Arlene Foster’s Stormont claims on Monday, it is not the EU, or the Irish Government, which is “using Northern Ireland to get its way”. If the UK really is trying to collapse talks with the EU, the North will be ground zero for a crash-out Brexit at year’s end.

Mrs Foster might do well to remember how recently and how absolutely Mr Johnson betrayed the DUP before jumping back on the madman’s bandwagon.