Afghanistan pullout: Biden's biggest call yet - will it be his most calamitous?

If you like neat lines, tidiness and ire symmetry, what's not to like about the decision of Joe Biden to pull American combat troops out of Afghanistan by 11 September 2021 - exactly 20 years on from 9/11?

In modern day America it often feels that all roads lead back to 9/11; the single most defining - and scarring - event since Pearl Harbor: the surprise attack by the Japanese on America's Pacific fleet, which would ultimately bring America into World War Two.

And so it was that 9/11 led to this country's longest military encounter. The attack on the Twin Towers, the plane that flew into the Pentagon, and the one that crashed into a field in Shanksville, Pennsylvania, were initially the spur for a surge of US nationalism. Young people - in fact people of all ages - were going along to armed forces recruitment offices wanting to sign up. America had come under attack; these patriots wanted to fight to defend the country the "land of the free", and seek revenge on those who would do the US harm.

And don't mistake this for some kind of kneejerk jingoism. It wasn't that. I knew many people - not just Americans - who were of a liberal bent and had been no great fans of all the doings of the US of A but who have a visceral sense this was a moment where you had to pick your team.

Were you on the side of the rule of law, free and fair elections, due process, sexual equality, universal education? Or were you on the side of those who would fly planes into buildings, or would stone people to death, or throw homosexuals off of buildings, or deny girls schooling? If that seems a massive over-simplification, maybe it is - but in the devastating aftermath of 9/11, that is how it seemed to many.

But by 2016 it was one of the factors that led to Donald Trump's election: the weariness of the "endless wars" as candidate Trump would refer to the quagmires of Afghanistan and Iraq; the wariness of America being able to act as the world's policeman.

Americans understandably wanted to pull up the drawbridge, bring the troops home, leave it to the people in those countries to sort out their own problems, and finally give up on the idea that a US model of liberal democracy was an exportable commodity that could be imposed. The liberal interventionist crusade was over.

Trump, if he had won last November, would have pulled out US troops, probably quicker. Although Joe Biden inherited Trump's promise to withdraw, in policy the easiest thing would have been to continue to sign the cheques to pay for American servicemen and women to stay in Afghanistan for another year. And then another. And another after that.

The political pressure was by no means overwhelming. If anything, the reverse. The defence top brass, the foreign policy establishment, America's allies abroad thought anything other than the status quo would be reckless. But one question was gnawing at the new president, and it was the one posed by Hillel the Elder back in biblical times: "If not now, then when":[]}