Syria is a European crisis as well as a Middle Eastern one, and the world’s worst human rights disaster in decades. Historians may one day tell us to what degree the west wasted a chance to force Bashar al-Assad to the negotiating table, had sufficient and timely pressure had been brought to bear on his forces, in particular through targeted strikes. That’s how Slobodan Milošević was forced to sign the 1995 Dayton agreement, which put an end to mass atrocities in Bosnia.

In the summer of 2013, a window of opportunity was arguably lost as a result of American hesitation. If archives are ever opened up, we may learn that it was the US failure to uphold red lines over chemical weapons use in Syria that emboldened Russia’s Vladimir Putin to launch his military intervention in support of a dictator whose army had been massacring civilians since 2011.

I’m not writing this to whitewash European policies. British restraint, or rather abstention, on Syria predated Barack Obama’s. And France, whose fighter planes were ready to take off in August 2013, could hardly go it alone. Still, trying to connect the dots between the Middle East, Russia, Europe, and how the US chooses to act or not act, remains important. The ravages of war in Europe’s vicinity, and the spillover effect of Middle Eastern chaos, are developments whose impact is yet to be fully measured.

There have been half a million deaths in Syria, and we’re still counting. The first victims of the slaughterhouse were in the Middle East, not Europe. Yet we are connected to these atrocities in ways that go beyond our on-and-off capacity for indignation as we sit watching television images of children being bombed in their hospital beds in eastern Ghouta.

In the heyday of post-cold war optimism, Europe was supposed to be able to export stability. Instead, in recent years, instability and chaos have spilled into Europe from the outside. The European project was born from the need to ensure the past wouldn’t repeat itself. Today Germany is a reluctant hegemon in Europe and an even more reluctant military actor. Britain and France are former colonial powers in the Middle East whose influence today looks insignificant.

Syria will haunt us for a long time yet. Since the fall of Raqqa last year, the crisis has gradually mutated into something resembling a world war, although the large powers involved in it – Russia, Iran, Turkey, the US – aren’t expressly in open warfare with one another. But they are vying for territorial control. Some experts like to draw a comparison with Lebanon’s 15-year conflict – by which measure Syria may be only at the midpoint of its proxy war.

Europeans are largely sidelined, however vocal our political leaders may at times choose to be. We haven’t yet fully fathomed how Syria’s catastrophe has affected how we relate to the world, to ourselves and to the values we like to profess. After 1945 we said “never again”, but never again is unfolding right before our eyes. Syria has become the absolute demonstration of our helplessness, and we collectively let that happen. Syria is the vortex in which a rules-based global order is fast unravelling. That should matter to us immensely because Europe has always had a greater stake in the UN system than the US has. When rules crumble, as happened with the 1930s League of Nations, we are well aware how beasts can rear their heads.

The outcome is a dizzying European passivity and powerlessness in the face of total war

Syria is where autocrats and neo-totalitarians are winning the day right now. Putin, Recep Tayyip Erdoğan of Turkey and Iran’s military theocracy hold the high ground – or are widely perceived as doing so, which matters perhaps even more. Meanwhile, the personality of Donald Trump hardly stands out as a reassuring beacon. When men such as these can define much of what happens, two contradictory but mutually reinforcing phenomena occur in Europe.

The first is the return of a fascination with the ruthless strongman. Europe’s far right, as well as its growing metastasis in mainstream politics, are the most fertile ground for this line of thought: no matter the human cost, nothing stops a leader for whom the end justifies the means. Civilians aren’t civilians: they’re “terrorists”. UN resolutions aren’t law: they’re just paper – stuff that can usefully lower the outrage of mushy liberals before bombers get back to the business of creating a desert that will be called peace.

Then there is the apathy of supposedly pacifist whataboutery. This is found on the radical left of Europe’s political spectrum, from London to Berlin and Athens. Its moral relativism drapes itself in “internationalism”. From the very beginning, Syria was too complex a crisis to identify sound allies, goes that thinking. The west is guilty, full stop. Regime change is bad – even when it is called for by desperate populations. Conflict is all about controlling oilfields. Sanctions and the stemming of financial flows can end it. Just talk and negotiate. Our pilots are as criminal as those of Putin – never mind the deliberate, repeated pounding of hospitals in eastern Ghouta. Beware the mainstream western media. If we stop meddling in Syria, things will improve. Iran and Russia are counterweights to age-old US imperialism.

The outcome is a dizzying European passivity and powerlessness in the face of total war unfolding just a few hours away. Of course, there are condemnations, statements by foreign ministers, and calls of “something must be done”. But our societies have fallen prey to inertia and confusion.

One day we will need to look back more closely at the chronology of events in which counter-terrorism, not the UN-backed notion of the “responsibility to protect” civilians, became our sole priority; and in which military intervention against Islamic State became politically palatable in 2014 not because Arabs and Yazidis were being butchered, but because western hostages had been beheaded. We’ll need to dig into how the necessary questioning of the west somehow morphed into widespread indifference to what authoritarian powers can get up to.

Syria is a tragedy for Europe not because it has occasionally awakened our righteous outrage (in fairly modest doses), nor because our continent’s politics have been upended by refugee arrivals. Syria is very much part of us because, while we like to believe we have looked at ourselves in the mirror after Europe’s 20th-century carnage, we’ve let a degree of nihilism creep into how we approach the hell that has been let loose not far from our borders. We’ve almost inoculated ourselves against shame. Syria is our moral defeat.

• Natalie Nougayrède is a Guardian columnist