All things considered, this may not be such a bad outcome. A reckoning was long overdue. The Bush-Blair invasion of Iraq was a historic mistake. Barack Obama’s Syria cop-out was shaming, for the opposite reason. Now the hugely costly 20-year Afghan intervention is ending in calamity, more refugee chaos, and the threat of renewed terrorism which, once again, will principally affect Europe.

If this is where US leadership leads, who needs it? When America plays global policeman, as self-described “liberal-neocons” say it must, too many people in too many places end up screaming “I can’t breathe!” America is either woefully absent – or its domineering engagement ends in tears. The cycle repeats. Fears grow that US allies are being dragged into another “forever war”, this time with China.

Selfish American behaviour during the pandemic was not untypical. Trump caused untold harm through denial and inaction. Biden’s administration has endangered millions by vaccine-hoarding. Afghanistan today is a geopolitical expression of this familiar phenomenon. Trump did not invent America First. Biden is merely its latest exponent.

The president’s televised speech last Monday was truly shocking to non-Americans. His undeserved contempt for Afghan forces and obliviousness to the sacrifices of Nato allies smacked of arrogance and betrayal. His claim that nation-building was never a US aim was grotesquely untrue. “Afghanistan was the ultimate nation-building mission,” George W Bush wrote in his 2010 memoir, Decision Points. “We had a moral obligation to leave behind something better.” Hear that, Joe?

Yet it was Biden’s apparent repudiation of the traditional US leadership role that rocked British and European establishments. “Endless military deployments of US forces” in overseas conflicts were not in the national interest, he declared. Afghanistan was solely about defending the “homeland”. For those raised in a world defined by American power and ringed by its permanent bases, this was stunning.

Armin Laschet, Angela Merkel’s choice to succeed her as Germany’s chancellor, called the withdrawal “the biggest debacle Nato has suffered since its founding”. Conservative MP Tom Tugendhat, an Afghan war veteran, decried “Britain’s biggest foreign policy disaster since Suez” – another fiasco, incidentally, to which the US contributed.

Hapless Boris Johnson meanwhile snuffles about like a pig stuck in the middle. Britain’s prime minister has shamelessly sucked up to Washington since burning his EU boats. Now, furious ministers and generals must bite their tongues – for fear of damaging the wider, precarious “special” relationship. That Brexit price-tag just keeps rising.

The obvious lesson for European leaders, and even Johnson, is that Washington cannot be relied upon, if it ever could. Afghanistan is the latest proof that the US, like every other nation state, ultimately acts in its own interest – as it perceives this at a particular moment in time – no matter what solemn blood promises have been made.

In short, American exceptionalism always was illusory. Greater European self-reliance is the only logical answer.

Post-1945, it suited the US to entrench its newfound physical and economic sway over Europe, and thereby contain its Soviet superpower rival. The resulting Truman doctrine, while championing universal freedoms, essentially pivoted on self-interest. Altruism had little to do with it. Now, with US power declining relative to China and new challenges arising, self-interest dictates re-evaluation, re-prioritising, and retrenchment.

This is the broader context in which the Afghan withdrawal should be understood – since Biden’s successors are unlikely to act very differently. EU states, with or without Britain, must finally make good on years of talk about building credible, independent European defence and security capabilities. In short, French president Emmanuel Macron is right, and Merkel is wrong.

All the same, it’s a mistake to keep beating up Biden. For sure, the withdrawal is dreadfully mismanaged. The US could and should have kept a minimal presence at the Bagram airbase, for deterrence purposes. The enemies of democracy have certainly been strengthened. There’s no doubt Afghans are paying a terrible price.

But calling time on the post-9/11 “forever wars”, as part of this necessary reformation of US foreign policy, was inevitable and unavoidable.

If Biden succeeds in his stated aims, future American global leadership will prioritise diplomacy, soft-power tools, economic and financial levers, technological advantage, intelligence-gathering and specialised defensive capabilities over brute military force, full-scale invasions, and indefinite armed occupations. Biden officials call it “smart power” for a new era. This is surely progress of a kind.

The shift is symbolised by Biden’s ending of Bush’s “global war on terror”. A policy review is expected to recommend reducing the worldwide US counter-terrorism footprint, which has grown exponentially since 2001. The new policy will reportedly look beyond Islamist terror to the rising domestic threat from far-right extremists.

A moratorium on drone strikes has been in place since January. New Pentagon guidelines will raise the threshold for launching military action and require field commanders to do more to avoid civilian casualties. It’s too late for Afghanistan, where thousands of non-combatants died. But it could reduce future bloodshed.

The Afghan project failed. The tarnished age of Pax Americana and the “endless military deployments” Biden deplored is thankfully drawing to a close. Nato – discredited, ill-led, and taken for granted – has had its day, too. A more balanced, more respectful US-Europe security relationship is required. Without it, there may be no western alliance left to lead.