Istanbul- The world seems awash in chaos and uncertainty, perhaps more so than at any point since the end of the Cold War.

Authoritarian-leaning leaders are on the rise, and liberal democracy itself seems under siege. The post-World War II order is fraying as fighting spills across borders and international institutions — built, at least in theory, to act as brakes on wanton slaughter — fail to provide solutions. Populist movements on both sides of the Atlantic are not just riding anti-establishment anger, but stoking fears of a religious “other,” this time Muslims.

These challenges have been crystallized, propelled and intensified by a conflagration once dismissed in the West as peripheral, to be filed, perhaps, under “Muslims killing Muslims”: the war in Syria.

Now in its seventh year, this war allowed to rage for so long, killing 400,000 Syrians and plunging millions more into misery, has sent shock waves around the world. Millions have fled to neighboring countries, some pushing on to Europe.

The notion that the postwar world would no longer let leaders indiscriminately kill their own citizens now seems in full retreat. The Syrian regime’s response to rebellion, continuing year after year, threatens to normalize levels of state brutality not seen in decades. All the while Bashar al-Assad invokes an excuse increasingly popular among the world’s governments since Sept. 11: He is “fighting terror.”

“Syria did not cause everything,” said the Syrian dissident Yassin al-Haj Saleh, a secular leftist who spent nearly two decades as a political prisoner under Mr. Assad’s father and predecessor, Hafez. “But yes, Syria changed the world.”

The United Nations Security Council is paralyzed. Aid agencies are overwhelmed. Even a United States missile strike on a Syrian military air base, ordered by President Trump in retaliation for a chemical attack on a rebel-held town, seems little more than a blip in the turmoil, the latest unilateral intervention in the war. Two weeks later, the Syrian regime, backed by Russia, continues its scorched-earth bombings.

There remains no consensus on what should have been or could still be done for Syria, or whether a more, or less, muscular international approach would have brought better results.

The Obama White House kept Syria at arm’s length, determined, understandably, to avoid the mistakes of the invasion and occupation of Iraq. And Western leaders surmised that unlike the 1990s civil war in Bosnia, the Syrian conflict could burn in isolation from their countries.

Moral or not, that calculation was incorrect. The crisis has crossed Europe’s doorstep and is roiling its politics.

The conflict began in 2011, with political protests. Syrian security forces cracked down, and with Western support stronger in rhetoric than reality, some of Assad’s opponents took up arms. The regime responded with mass detentions, torture, starvation sieges and bombing of rebel-held areas. Extremist jihadists arose, with ISIS eventually declaring a caliphate and fomenting violence in Europe.

More than five million Syrians have fled their country. Hundreds of thousands joined a refugee trail across the Mediterranean Sea to Europe.

Images of crowds of desperate refugees — and of the extreme violence they had faced at home — were used by politicians to fuel fears of Islam, and of Muslims. That lifted far-right European parties already riding on resentment of immigrants, from Finland to Hungary.

The refugee crisis has posed one of the biggest challenges in memory to the cohesion of the European Union and some of its core values: freedom of movement, common borders, pluralism. It heightened anxieties over identity and culture, feeding off economic insecurity and mistrust of governing elites that grew over decades with globalization and financial crises.

Suddenly European countries were erecting fences and internment camps to stop migrants. While Germany welcomed refugees, other countries resisted sharing the burden. The far right spoke of protecting white, Christian Europe. Even the Brexit campaign played, in part, on fears of the refugees.

In the United States, as in Europe, right-wing extremists are among those embracing authoritarian, indiscriminately violent responses to perceived “Islamist” threats. White nationalists like Richard Spencer and David Duke, the former Ku Klux Klan leader, post adoring pictures on social media of Assad, who portrays himself as a bulwark against extremism.

In my decade of covering violence against civilians in the Middle East, mass murder by states has often seemed less gripping to Western audiences than far smaller numbers of theatrically staged killings — horrific as they are — by ISIS and its Qaeda predecessors.

The United States’ own “war on terror” played a part in making violations of humanitarian and legal norms routine: detentions at Guantánamo Bay, the torture at Abu Ghraib and the continuing drone and air wars with mounting civilian tolls in Syria, Iraq, Yemen and elsewhere.

Then, too, Syria’s war broke out when the global stage was set for division and ineffectiveness. Russia was eager for a bigger role, the United States was retreating, Europe was consumed with internal problems. Russia and the United States saw opposite interests in Syria, deadlocking the Security Council.

The New York Times