Evelyn Reynolds

It was as close as Donald Trump might get to a lucid statement of his governing doctrine. “I may do it. I may not do it,” the president said to reporters on the White House lawn. “Nobody knows what I’m going to do.”The question was about joining Israeli air strikes on Iran’s nuclear facilities. Days later, US bombers were on their way. Some expected it to happen. Others, including Keir Starmer, had gone on record to say they didn’t. No one had known. The unpredictability doctrine wouldn’t have been violated either way.It applies also in economic and domestic policy. Trump’s boast of inscrutability could have been made about tariff rates, or a decision to deploy marines against US citizens who defy his immigration agency.Volatile inconsistency is a trait of the presidential personality, but also a learned management technique. Keeping everyone around you guessing, lurching from charm to menaces, swapping and dropping favourites on a whim – these are methods of coercive control. They generate disorientation and vulnerability. People who are braced for sudden mood swings must hang on the leader’s every word, looking for cues, awaiting instruction. Individual agency is lost, dependency is induced. It is something cult leaders do.A method that works with a quasi-monarchical entourage is poorly suited to international affairs. Foreign leaders are not White House courtiers. They might seek the US president’s favour in trade or fear his military wrath, but always with competing national interests in the background. On the world stage, Trump will never feel the unalloyed devotion he gets from worshippers at a Maga rally, which is one reason why he hates to travel.That tension is palpable at this week’s Nato summit in The Hague. Trump makes no secret of his disdain for European democracies. He resents their reliance on the Pentagon for security. He is unconvinced that defending their continent, especially the corner of it under violent assault from Russia, is the US’s problem. The threat he briefly made in his first term to pull out of Nato if other members didn’t start paying their way still hangs over the alliance. European leaders must strive to keep Trump onside while contingency planning for the day he decides to abandon them.Matthew Whitaker, the US’s permanent representative at Nato, tried to be reassuring on that point at the summit, declaring that it “has never been more engaged”. But he also conceded ignorance of what Trump might actually do. “I don’t want … to claim to be able to read his mind and know what he’s going to say.”That is the doctrine: nobody knows. This forces Nato members into an awkward dance, performing for Trump’s benefit while also working around him. They want to impress him with their financial ambition, pledging to spend 5% of their national GDP on defence by 2035. But they know also not to expect any reciprocal commitment, or none that can be trusted.War in the Middle East ramps the uncertainty up to new heights. European leaders need to stay focused on Ukraine and the prospect of Russia turning its territorial aggression on some other portion of Nato’s eastern flank. Vladimir Putin sees no legitimacy in borders that were drawn by the collapse of the Soviet Union. He has also geared Russia’s economy, political apparatus and propaganda machinery to assume perpetual war with the west. One lesson from Ukraine’s plight is to assume that when Putin says he is going to fight, he means it. Another is that, while deterrence is expensive, it is cheaper than the war that comes when the Kremlin feels confidently undeterred.These calculations keep Europeans up at night, but not Trump. He doesn’t recognise Russia as the aggressor in Ukraine and would happily see the war end on terms that leave Nato humiliated and Putin emboldened, and signal an epoch-defining shift in the balance of global power away from democracy.But framing the choice in grand geostrategic terms obscures pettier motives, which are often the salient ones with Trump. He doesn’t want to take Kyiv’s side because that is what Joe Biden did. It isn’t his cause and so he thinks it is dumb.This is not the case with Iran. US allies are required, in public at least, to judge Trump’s military intervention as though it were made according to a conventional diplomatic and strategic calculus: the prospect of Tehran wielding powers of nuclear apocalypse is truly abhorrent; negotiation was not bearing fruit. Maybe there was reason to dispute US intelligence assessments that said the threshold of weapons-readiness was not imminent. Maybe the time to act really was at hand.But those are rationalising arguments, retrofitted to a choice that Trump made as much from vanity as any more sophisticated motive. He was bounced into war by Benjamin Netanyahu. The Israeli prime minister appears to have gamed the US president’s aversion to looking weak and his limitless appetite for glory. Early Israeli success – an extraordinary feat of military intelligence that took out senior Iranian commanders and assets – offered Trump the prospect of climbing aboard a winning operation and grabbing credit for victory.Hints that regime change was on the agenda may have prodded Ali Khamenei, Iran’s supreme leader, towards a ceasefire on the basis that early capitulation with some power retained, while unpalatable, is preferable to assassination. Senior White House officials insisted the war aims were limited to containment of the nuclear threat, but since they hadn’t even known a war was coming their authority on the matter is questionable.Trump’s supporters say this is proof that his volatile style works. In strategic studies it is known as the “madman theory”. Discarding guardrails, looking ready to do something irrational, forces an enemy to choose caution. The obvious risk is that it also teaches the rest of the world the merit of madness. Iran’s rulers will be more convinced than ever that only nuclear weapons can guarantee their sovereignty. (That view would persist through regime change, since none of the viable scenarios result in a flowering of pro-western democracy in the region. Tehran’s atomic ambitions may be set back by years, but the cause of negotiated, multilateral non-proliferation is also in tatters.)That doesn’t interest Trump. He thinks in terms of easy wins, not complex consequences. Hence his palpable irritation with Israel and Iran for violating the ceasefire and generally not knowing “what the fuck they’re doing”. He is aware that he looks played by Netanyahu, much as he once showed a flicker of frustration with Putin for “tapping” him along in negotiations to end the war in Ukraine. He promised US voters deals. He gets cross when the world withholds them from him.This is a natural function of the unpredictability doctrine. Telling other countries they can never know what you’ll do makes them less responsive to diplomacy; less biddable to the whim of a US president. A vicious cycle then begins. Trump relies on his volatile persona to assert control in situations that he doesn’t understand, generating chaos that exposes his impotence, which in turn provokes him to tug in more arbitrary fury at his levers of power.For European democracies this is debilitating. It is hard to coordinate defence against external threats when the paramount power in your alliance is the origin of so much instability. But Nato leaders will get no respite from the uncertainty as long as Trump sits in the White House. The thing they most need from him – reliability – is the one thing he is destined by personality and doctrine never to provide.

Rafael Behr is a Guardian columnist More