You may know Bana. You may have seen her face on Facebook; you may have caught a glimpse of one of her videos on Twitter. Bana is a seven-year-old, living in East Aleppo. She tweets – or rather her mother does for her, a setup giving rise to a thousand conspiracy theories – about rubble and buried school friends. Through the power of the internet, we can send her Harry Potter books, but not drinking water. Such is the deceptive promise of our connected world.

Time is running out for Bana. She knows it, we know it. Last week, her house was bombed out, and she and her mother took to living with friends. East Aleppo has been the heart of Syria’s insurgency, but in the last few weeks, government forces – many of them Shia fighters from neighbouring Iraq and Iran – have taken control of 50 per cent of the land previously held by rebels. Refugee agencies estimate 34,000 civilians were displaced last week. The UN envoy for Syria, Staffan de Mistura, estimates the city will fall by the New Year. President Assad’s forces – and their Russian funders – are not known for showing mercy to civilians.

Who betrayed Bana? How did it come to this? Even as the West’s liberals weep goodbye to President Obama, bracing ourselves for his successor, we should ask ourselves some tough questions about his – and our – complicity in Syria.

President Assad maintains, as he has done since the first pro-democratic protests began in 2011, those who took up arms against his rule are terrorists and radical Islamists to boot. All those who oppose him, by extension, are Isis sympathisers, a murderous monolith of extremists. It is the natural responsibility of modern governments to destroy Islamist killers. Looking at the headless corpses littering the ground of Raqqa, who could disagree?

In pictures: Children play underground in Syria Show all 8 1 /8 In pictures: Children play underground in Syria In pictures: Children play underground in Syria A child plays in the ball pit at the 'Land of Childhood,' an underground playground in a besieged town in Syria Unicef In pictures: Children play underground in Syria Abdulaziz, 10, plays in the 'Land of Childhood' underground playground in Syria Unicef In pictures: Children play underground in Syria Boys look through a show window inside the tunnel that provides a safe passage for children between the two basements that form the 'Land of Childhood' in a besieged town in Syria Unicef In pictures: Children play underground in Syria Children play at the underground 'Land of Childhood' in a besieged town in Syria Unicef In pictures: Children play underground in Syria Two girls play at the 'Land of Childhood' underground playground in a besieged town in Syria Unicef In pictures: Children play underground in Syria Children on the ride on a ferris wheel at the 'Land of Childhood', an underground playground in a besieged town in Syria Unicef In pictures: Children play underground in Syria Seven-year-old Massa at the "Land of Childhood" underground playground in a besieged town in Syria Unicef In pictures: Children play underground in Syria Children wait in line to buy sweets at the 'Land of Childhood,' an underground playground in a besieged town in Syria Unicef

Assad’s critics have long known Isis is not his enemy. For years, evidence has built up about his government’s nurturing of Isis cells, cultivated first in order to be sent back into Iraq, bogging down the Americans, then to carve up Syria in an Assad-Isis pact to squeeze more secular rebels on multiple fronts. This week, the Daily Beast is publishing a series of extraordinary interviews with former Assadists, attesting to the longevity of the President’s links with anti-Western Islamists. But while the details are new, the gist is not. In early 2016, a series of leaked documents proved that Assadist commanders had colluded with Isis fighters to coordinate their attacks on moderate cities, including Palmyra, and that the Syrian government had been paying Isis for the oil pumped from looted air fields.

Such details seem to have been lost on the newest arrival to the international scene, Donald Trump. Assad’s ally, Vladimir Putin, has consistently made the case that Western governments should be supporting President Assad as the last bulwark against Islamist terror. Russia’s own role as the last defender of white “Christianity” is the fevered dream of a thousand white supremacist Twitter accounts. Thus, throughout the American election campaign, Donald Trump has repeated Putin’s talking points; now, after his election, Democrat-appointed diplomats are scrambling to tie down international agreements keeping Assad out of Aleppo before President Trump takes over and waves the Syrians in. Their chances are not good.

Meanwhile, in America, liberals mourn the dying days of Barack Obama’s presidency. Against the advent of Trump, any outgoing leader would look eloquent, heroic and presidential. In a much-shared profile in The New Yorker, David Remnick wrote of Trump’s victory as a personal loss for Obama, “an American tragedy”. There is a strong temptation to recast the last eight years as an idyll of internationalist humanitarianism.

Yet for Bana and her younger brother, hiding amid the rubble in Aleppo, Trump’s victory may have little effect. The damage to them has been done; it has been done over the last five years. Consistently, Obama has sought to negotiate with Vladimir Putin; consistently, Russian-Syrian promises have been broken, and ignored by a conflict-averse America. Obama once promised the use of chemical weapons by President Assad would be a “red line” after which retribution must follow – and we all know how that turned out.

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He was not helped by Britain’s left; Ed Miliband’s recent attempts to recast himself as an elder statesman sit uneasily with the political games he played during Parliament’s 2013 vote on Syrian intervention. Having promised to support a government bill preparing the way for strikes on Assadist targets, he reneged at the last moment, afraid to lose support in his own party to Diane Abbott and the anti-interventionist hard left. We know how that turned out, too.

Bana, I suspect, will survive, nominally. Siege victims who become international symbols have a funny way of being rescued and feted by the victors. How many of her friends, family members, teachers, will die or have already died may be quietly brushed away. But those in America keen to burnish Obama as the last, great President before the Trump tragedy, will have to answer to Bana's mother.