These past few days have been a watershed for Europe. I’m not thinking about Brexit, but about Syria – which increasingly looks like our 21st-century Spanish civil war. Western and European defeat in Syria (by which I mean political and moral, not just military defeat) has parallels with the 1930s when democracies were unable or unwilling to stand up to authoritarians when it mattered, or even to play any kind of meaningful role in preventing a catastrophe that would soon enough engulf them, too.

Events in north-eastern Syria are obviously tragic, if not lethal, for the tens of thousands of people caught up in them locally. But they will also have an impact on Europe in more ways than we perhaps care to acknowledge. Donald Trump himself has said as much, casually pointing out that Islamic State-connected foreign fighters now on the loose would make their way back to Europe. He made clear that that is a problem Europe would have to handle alone. As bad as that prospect is, it is only one part of a wider picture that should make Europeans feel desolate: at a crucial moment in history, the Russia-Iran authoritarian axis is now fully victorious on Europe’s doorstep.

Quick guide What is happening in north-eastern Syria? Show Hide Who is in control in north-eastern Syria? Until Turkey launched its offensive there on 9 October, the region was controlled by the Syrian Democratic Forces (SDF), which comprises militia groups representing a range of ethnicities, though its backbone is Kurdish. Since the Turkish incursion, the SDF has lost much of its territory and appears to be losing its grip on key cities. On 13 October, Kurdish leaders agreed to allow Syrian regime forces to enter some cities to protect them from being captured by Turkey and its allies. The deal effectively hands over control of huge swathes of the region to Damascus. That leaves north-eastern Syria divided between Syrian regime forces, Syrian opposition militia and their Turkish allies, and areas still held by the SDF – for now. On 17 October Turkish president, Recep Tayyip Erdoğan, agreed with US vice-president Mike Pence, to suspend Ankara’s operation for five days in order to allow Kurdish troops to withdraw. The following week, on 22 October, Erdoğan and his Russian counterpart, Vladimir Putin agreed on the parameters of the proposed Turkish “safe zone” in Syria. How did the SDF come to control the region? Before the SDF was formed in 2015, the Kurds had created their own militias who mobilised during the Syrian civil war to defend Kurdish cities and villages and carve out what they hoped would eventually at least become a semi-autonomous province. In late 2014, the Kurds were struggling to fend off an Islamic State siege of Kobane, a major city under their control. With US support, including arms and airstrikes, the Kurds managed to beat back Isis and went on to win a string of victories against the radical militant group. Along the way the fighters absorbed non-Kurdish groups, changed their name to the SDF and grew to include 60,000 soldiers. Why does Turkey oppose the Kurds? For years, Turkey has watched the growing ties between the US and SDF with alarm. Significant numbers of the Kurds in the SDF were also members of the People’s Protection Units (YPG), an offshoot of the Kurdistan Workers’ party (PKK) that has fought an insurgency against the Turkish state for more than 35 years in which as many as 40,000 people have died. The PKK initially called for independence and now demands greater autonomy for Kurds inside Turkey. Turkey claims the PKK has continued to wage war on the Turkish state, even as it has assisted in the fight against Isis. The PKK is listed as a terrorist group by Turkey, the US, the UK, Nato and others and this has proved awkward for the US and its allies, who have chosen to downplay the SDF’s links to the PKK, preferring to focus on their shared objective of defeating Isis. What are Turkey’s objectives on its southern border? Turkey aims firstly to push the SDF away from its border, creating a 20-mile (32km) buffer zone that would have been jointly patrolled by Turkish and US troops until Trump’s recent announcement that American soldiers would withdraw from the region. Erdoğan has also said he would seek to relocate more than 1 million Syrian refugees in this “safe zone”, both removing them from his country (where their presence has started to create a backlash) and complicating the demographic mix in what he fears could become an autonomous Kurdish state on his border. How would a Turkish incursion impact on Isis? Nearly 11,000 Isis fighters, including almost 2,000 foreigners, and tens of thousands of their wives and children, are being held in detention camps and hastily fortified prisons across north-eastern Syria. SDF leaders have warned they cannot guarantee the security of these prisoners if they are forced to redeploy their forces to the frontlines of a war against Turkey. They also fear Isis could use the chaos of war to mount attacks to free their fighters or reclaim territory.

On 11 October, it was reported that at least five detained Isis fighters had escaped a prison in the region. Two days later, 750 foreign women affiliated to Isis and their children managed to break out of a secure annex in the Ain Issa camp for displaced people, according to SDF officials. It is unclear which detention sites the SDF still controls and the status of the prisoners inside. Michael Safi

Bashar al-Assad’s forces, aided by Russian and Iranian military involvement, are now pushing north to retake territory that the anti-Isis western-led coalition and its Kurdish ground troops had managed in recent years to keep out of the Syrian dictator’s and his enablers’ reach. With Trump’s sudden decision to pull troops out, and the fast-moving events that ensued, Russia is losing no time moving in to fill the void. The Russia-Iran axis is empowered as never before, and that’s been facilitated not just by Trump’s recklessness and his “America first” doctrine, but by the division, confusion and inward-looking state of all our western democracies. The resemblance with the 1930s screams out at you.

It’s true that Europeans are currently scrambling to cobble together sanctions against Turkey for its military onslaught against Kurdish-held lands inside Syria, but not much continental unity is on offer. Whatever pressure some capitals may muster looks unlikely to shape events. Nor do European governments seem in any position to effectively weigh on Russia as it wreaks yet more havoc in their vicinity. Essentially, Europe is the bystander in a nightmare it didn’t see coming, nor had the means to avert.

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If you think Syria is just a distant quarrel that we Europeans can easily turn our gaze away from, think again. The 2015 refugee crisis, in which Syria’s killing fields played no small role (with, at its core, a dictator’s strategy of turning his army against his own country’s population to hold on to power, producing mass movements of people) surely proved how badly European politics and our continent’s cohesion can be affected by chaos and full-on violence in its neighbourhood.

Nor is the authoritarian axis just a handful of strongmen (Vladimir Putin, Ayatollah Ali Khamenei, Recep Tayyip Erdoğan) playing power games across a limited geopolitical chessboard. The victory they are in the process of clinching sends a much larger message about how fast an entire world system can come undone – a world in which Europeans could still hope that some principles, such as a basic observance of alliances, might still bear a degree of importance.

It may not be too soon to draw a few lessons from what’s unfolding. With Trump’s sellout of allies in Syria, US security guarantees to Europe as we’ve known them are fast evaporating before our eyes. Trump’s move has given new meaning to what we already knew about his overall disdain for Nato. Be sure that little of this will have been lost on authoritarian leaders who believe their global time has come and that all they need to do is seize opportunities and pick up the spoils of a disintegrating western-led international order. To taste a bit of that thinking, read Putin-propagandist Vladislav Surkov’s writings earlier this year about Russia’s role in the world as a model for nationalism and expansion based on brute force.

No less daunting is the human toll – another shattering of the body of human rights conventions that Europe is meant to be one of the guardians of, but finds itself entirely powerless to salvage. Predictions are that Isis will try to regroup in the general mayhem. But already on display is how the Turkish, Syrian and Russian forces vying for control are leaving countless massacred civilians in their wake. We’ve by now had ample evidence of the extremes to which state-sponsored mass atrocities can lead in this near-decade of war in Syria. If anyone still held any doubts as to their deliberate nature, documented reports of Russia’s systematic bombing of hospitals will have perhaps dispelled them once and for all.

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This multilayered disaster in the Middle East will have dire consequences for European security (the terrorist threat), our domestic politics (the far right is entirely in tune with Assad and Putin, and is already gloating) and our societies at large. That’s because Assad’s Russia-backed victory in Syria will register as a decisive chapter in an era of fear, fragmentation and disinformation. That Brexit is playing out against this backdrop is almost a coincidental sideshow – however symbolic of the deeper trends at work. These days Europeans rightly scrutinise Spain and Catalonia, and ponder the outcome of elections in Poland and Hungary (has populism peaked, or is it still on the march?), but right now that feels narrow-minded, given the magnitude of what is unfolding not far from us.

Historical analogies only go so far, but what’s different now is that we’re not just having to think about the domestic realities of demagoguery, xenophobia and homegrown illiberalism. We in Europe have to break out of our navel-gazing and see the bigger picture: what’s happening is no less than an ideological battle between democracy and authoritarianism in which our fate is intimately connected to those who find themselves in the crosshairs of Syria’s tragedy. In that sense, Syria is indeed the Spanish civil war of our times. Just as it was in the 1930s when totalitarianism was on the rise, it would be delusional to think that what we’ve done and haven’t done about it won’t come back to haunt us.

• Natalie Nougayrède is a Guardian columnist and leader writer