When a freshly elected Joe Biden had his first transatlantic phone conversation with Boris Johnson, Number 10 bragged that the prime minister was at the top of the list on the new American president’s call sheet. Downing Street flourished this as evidence that, whatever differences between the two men there might have been in the past, the “special relationship” was as warm and deep as ever. Now we know differently. When it came to the calls that mattered over Afghanistan, Mr Johnson’s capacity to influence Mr Biden was less than that of the president’s dog. The withdrawal of what remained of the Nato presence in Afghanistan was dictated by abrupt and unilateral decisions made in Washington. Ministers privately admit that not only did they fail to see a resurgent Taliban coming, they have been reduced to second-guessing what the United States will do next. A callous and cynical Donald Trump struck a terrible cut-and-run deal with the Taliban. Mr Biden foolishly chose to carry on with it and in a fashion so calamitous that it has surrendered Afghanistan back to the murderous extremists that western forces went in to evict two decades ago. This wretched denouement has been seared into the world’s consciousness by images of frantic mothers throwing their babies over razor wire fences at Kabul airport and desperate souls clinging to the fuselage of departing US transport planes before losing grip and falling to their deaths. The UK and other Nato members had the power only to protest to the Americans after the tragic event. There has been much deserved mockery of the prime minister for going off on holiday even as the Taliban advanced on the gates of Kabul. The foreign secretary, Dominic Raab, is taking heavier flak for being by his sun-lounger. It was definitely a dereliction of duty to be on the beach at such a grave moment, but behind that lies a much more brutal truth, one that many Britons, and the Conservative party in particular, find difficult to digest. It would have made little essential difference to the big picture if the two men had been chained to their desks. Even were Mr Johnson a figure with sufficient credentials in statesmanship to bend the president’s ear about the disastrous course he chose, the UK had scant moral or practical authority to call on because virtually all of our combat troops were withdrawn seven years ago. Britain’s powerlessness was the subtext to the hand-wringing speech that the prime minister gave to the emergency session of the Commons. He basically conceded that the ability to shape events in Afghanistan, or even to accurately forecast them, was beyond the UK government. Theresa May witheringly asked the man who supplanted her: “Where is Global Britain on the streets of Kabul?” There were moving words about the sacrifices made over the past 20 years and heated ones about betrayal, especially from MPs who served in Afghanistan as part of the Nato coalition assembled after the attacks on the Twin Towers. I have never heard so much fury so ferociously expressed by Conservative MPs about the behaviour of the US. Behind their hot anger was a cold fear: the foreboding sense of an impotent Britain friendless in a frightening world. Since 1945, there have been two dominant strands of British opinion about the complicated relationship with America. Most of the foreign policy establishment and nearly all prime ministers have adopted the Atlanticist view. This holds that Britain maximises its influence over the US and its heft in the world by gluing itself to whoever occupies the Oval Office. There have been some exceptions, such as Harold Wilson’s shrewd choice to stay out of the Vietnam war, but “hug them close” has been the rule. It was that impulse that drove Tony Blair to declare that he would “stand shoulder to shoulder” with America in the immediate aftermath of 9/11 and later promise George W Bush that he would be “with you to the end” in Iraq. Britain’s investment of a lot of its own blood, treasure and reputation in American-led interventions is why the west’s humiliation in Afghanistan is felt so especially keenly among so many MPs. The other strand of opinion, which became particularly sharp after the Iraq debacle, is that the US is an unbearably dominant power that throws its weight around with reckless arrogance. This view has been especially vehement on the left. Almost none of those on the left who are bewailing what will befall Afghanistan under renewed Taliban rule were previously to be heard urging Washington to deploy more of its firepower there. While apparently opposed, the Atlanticist and the anti-American view have something fundamental in common: they assume US power and the will to wield it. A more introverted US will confound the foundational assumptions of both those who look to America for leadership of the free world and those who hold America responsible for all the planet’s ills. Jihadists will take encouragement from the Taliban takeover and there’s a clear risk of Afghanistan becoming a breeding ground for terror as it was when it harboured al-Qaida. Mr Biden has sown doubt about the bankability of US security guarantees to other allies and undercut his hopes of co-ordinating the democracies to take a united stand against the autocracies. China and Russia will be emboldened in their conviction that the west does not have the stamina or the resolve to successfully defend liberal values or come to the aid of people in jeopardy. When Chinese generals are war-gaming an invasion of Taiwan, they will be that bit much more likely to take the gamble that the US will not intervene to stop them. The Kremlin will be inclined to think that it can play more of its deadly games on its borders. The resurgence in Afghanistan of one of the world’s most viciously reactionary cults will encourage dictators and wannabe ones the world over to behave more badly to their neighbours or their own people, or both. Those who have wanted less America will discover that it can be alarming to get what you wished for. Those who have looked to America for global leadership will have to think hard about alternatives. Emmanuel Macron contends that Europe should recognise that it can no longer depend on the US to provide its security and protect its interests and must strive to achieve “strategic autonomy”. This idea stirred into life when Barack Obama pivoted towards Asia and gained more traction when the Trump presidency so undermined the presumption that America is a reliable ally. In theory, the European democracies are rich enough and populous enough to have the capacity to confront Russian adventurism and stand up to Chinese aggression. In practice, European leaders have failed to summon the will, make the tough choices or mobilise the resources. Ben Wallace, the defence secretary, says he tried to assemble a coalition of Nato states willing to carry on in Afghanistan. The French and the Germans weren’t interested and I’m highly sceptical that the British government was truly serious. Mr Johnson suggested they weren’t when he told MPs that it was an “illusion” to think that the mission could carry on without the Americans and expressed doubt that either voters or parliament would support dispatching large numbers of UK troops back to Afghanistan. If we are entering an era of American disengagement, the questions are acute for a Britain that chose to estrange itself from the liberal democracies in its neighbourhood at the same time as the US was becoming a less dependable partner. Some plausibly conjecture that the future is a new world disorder in which the great powers jostle for predominance and norms of international conduct are trampled underfoot. This will be a rough place for a country in the north-east Atlantic with lots of vital interests around the globe, but not the means to safeguard them by itself and no one it can count on as an all-weather friend. Cuts to defence spending have left Britain with its smallest armed forces since before the First World War. Our nation’s previous reputation as a superpower of “soft power” has been weakened by Brexit and the fading of its influence in Washington and further sapped by savage cuts to the aid budget. Britain hasn’t the clout to act by itself, but has diminished its ability to persuade others to act with it. “Very well, alone” did good service for Winston Churchill as a wartime rallying cry in 1940. British impotence in Afghanistan demonstrates that it is an utterly hopeless strategy for survival in the 21st century. Andrew Rawnsley is Chief Political Commentator of the Observer