BEIRUT—Here in Lebanon’s capital over the weekend the center-city streets were as calm as they ever are. Locals drinking coffee at sidewalk cafés in the busy, smelly shopping district of Hamra sat back, smoked and watched the traffic jam up, as it usually does. Overhead, air traffic was also back to normal. Once the fear subsided of missiles flying over Lebanese airspace to hit neighboring Syria, almost all airlines had returned to their normal routes.

Despite a lot of hand wringing, some leery predictions about World War III kicking off just over the border, and the fact that the site of one of the attacks, Barzeh near Damascus, is only around a 100-kilometer drive away from those Beirut coffee shops, Lebanon’s weekend ended quietly. Most pundits wrote off Donald Trump’s “mission accomplished” as a symbolic gesture that was unlikely to have much impact on the brutal impasse of the Syrian civil war, now in its eighth year. The world press has turned to new tweets, new headlines.

But as the conflict grinds on that has killed more than half a million people and displaced more than 12 million, one thing becomes increasingly clear: what happened in Syria over the weekend, what has happened in Syria over the past seven years, and what will happen in Syria in the future is going to affect all of us, whether we like it or not and whether we think we’re involved or not—and probably in ways we cannot even begin to imagine today.

When the Obama administration, and other western governments, decided in 2013 to (mostly) stay out of the internal fighting in Syria despite the crossing of the chemical weapons “red line," they could not have known what was coming.

They could not have known that Syrian leader Bashar al-Assad’s accusation that the revolutionaries in his country were all foreigners or Islamic extremists would become a self-fulfilling prophecy. They could not have predicted that the power vacuum in Syria would so empower former members of al Qaeda from Iraq that they would establish a medieval-style caliphate, the so-called Islamic State, complete with beheadings and commemorative gold coins. They could not have guessed that as a result people in Europe and the United States now fear they might be stabbed by random strangers, or knocked down by a car that’s being used as a weapon on any street, in any town, anywhere.

Nor could they have foreseen that by 2018 there would be more than half a dozen countries inside Syria fighting their own proxy wars—Russia, Iran, Saudi Arabia, Qatar, the United States, Turkey and Israel, among them—and that at least half a dozen other countries would be directly impacted by it.

They would have had no idea that in five years, the European Union would be so buffeted by the distorted specter of immigration by huddled masses of asylum seekers that the refugee issue would come close to endangering the E.U.’s very existence.

Just one example: in this month’s elections in Hungary, Prime Minister Viktor Orban used locals’ fears of immigration to help him win a third consecutive term. Yet, just as in eastern Germany in last year’s federal elections, many of the people who voted for Orban’s populist, anti-immigration and euroskeptic platform had never even met a Syrian refugee.

Nor could anyone have predicted the course taken by Turkey, which at that early stage seven years ago, was still vying to become part of the European Union. Today Turkey’s emboldened leader, Recep Tayyip Erdogan, becomes more autocratic by the day. This NATO member is able to act with such impunity because Europe needs him to keep its furthest borders closed to terrorists from the Islamic State group as well as the political poison that is immigration. But the chances he will ever join the European club are now slim to none.

“ 2012 in Syria, that’s where we mark the beginning of the end of the international liberal order that evolved after World War II. ”

The Syrian crisis has been like pouring water onto a potholed street in the dead of winter. The water freezes, then expands and as it does, it widens the existing cracks in the road. As the chief political commentator for the British newspaper the Observer wrote this weekend, behavior in Syria has “shredded international norms about the conduct of war.” But it’s not just those norms that are being shredded. You have to wonder if one day, historians will look back and conclude that, “Oh yes, 2012 in Syria, that’s where we mark the beginning of the end of the international liberal order that evolved after World War II.”

After all, the United Nations Security Council, the organization set up to keep world peace after WWII, has been made a fool of over this. It may not have been the most effective or even-handed organization in the first place, but it has been rendered almost completely irrelevant by the Syrian crisis. As have multiple other organizations including chemicals weapons inspectors, aid organizations and the interlocutors of international justice.

Commentators, including British opposition leader Jeremy Corbyn, have argued there should have been a U.N. mandate for the missile strike this past weekend. But given the ongoing inefficacy of the international community and the uncompromising positions held by all those directly involved, you’d be tempted to ask why anyone would bother. Nobody does what they say anyway.

There is a personal aspect to this despairing point of view. Many of us have helplessly watched Syrian friends go through the stages: from hope in 2011 during the Arab Spring that the economic injustice and political oppression they had dealt with all their lives might be vanquished by peaceful means, to horror and grief over dead or missing friends and family, and urgent attempts to try to help from afar, to wanting to drop everything and go and fight. Then finally on to—and this was perhaps most shocking—disinterest, because they just couldn’t take it anymore. Crisis fatigue. They had to turn away to save their own sanity.

“We have lost,” a Syrian journalist friend told me recently. He had left the country after founding an opposition newspaper and now has a German passport. “We just have to admit it. Syria as we know it doesn’t exist anymore.”

“We don’t have a country anymore,” another friend said, noting that most of her fellow idealists who aspired to things like the freedom to vote and protest, and who opposed al-Assad at the start of the revolution and thought peaceful protests in the face of violence could work, are now just depressed at the international community’s ongoing hypocrisy. A generation of young people have lost faith in the system—and they’re not only Arabs.

The Syrian “butterfly effect,” if one can use such a term for something that begins with a cataclysm, will continue to be felt for generations, often in unpredictable ways, and sometimes perhaps even in positive ones. In a country like Germany, Syrian migrants are bringing new energy and experience to the culture. Despite what they’ve been through, or because of it, they cherish every small kindness and they are still determined to change their world for the better.

Recent political trends have favored politicians who would withdraw from world affairs to make, they claim, their countries “great again.” But the Syrian crisis teaches us that the modern world is not that simple. We are all connected economically, geopolitically, digitally, ethically—inextricably. Right now, nobody knows how to solve the Syrian problem. Nor does anybody know what would have happened had there been some sort of intervention five or six or seven years ago.

The only thing that is clear this week is that it will be hard for any of us, anywhere, to avoid the impact events in Syria have now and in the future, whether we believe we are involved or not. We all need to understand that. “Mission accomplished” is just a phrase, not the end of the story, not the beginning of a solution.