When Russian President Vladimir Putin ordered his troops to invade Ukraine at dawn on February 24, 2022, everything changed, not just for Europe but for the world. The historical clock had been turned back.

As soon as a major military power launched a war of conquest against a peaceful neighbor, we returned to a world in which power is asserted through violence and borders are drawn with blood. The defining geopolitical principle of the late twentieth and early twenty-first century was overturned. Non-violent negotiations and peace were out; unilateral assertions of strength were back in.

Though there have been numerous wars in recent decades, they were mostly regional in scope and occurred on the periphery of geopolitical fault lines. There was no hint of a global Sarajevo - a war requiring international intervention, like in Bosnia in the 1990s, but on a much larger scale. The automatic stabilizers worked reliably, and the United States, the sole superpower, still served as the guarantor of order - or so it seemed, until that world splintered before our eyes with no better alternative in sight.

Behind Putin's invasion lies neo-imperial Russian irredentism. Putin wants to revise the geopolitical conditions that have prevailed since the collapse of the Soviet Union. This kind of revisionist project is inherently dangerous, because it implies an assertion of dominance, even supremacy, and so requires war, not only against smaller neighbors and regional powers, but also against global powers (which have a stake in the outcome, even if they usually remain in the background).

As has long been apparent, the main geopolitical axis of the twenty-first century will be the relationship between the US and China. If the two superpowers can reach a strategic understanding and cooperate with each other, our chances of a peaceful future would increase sharply. If they cannot, the opposite will be true.

Complicating matters is the fact that the old world order - based mainly on America's liberal principles and Western supremacy - is losing strength and raising many questions. What consequences will follow from the proliferation of armed challenges to the existing world order? Could Pax Americana give way to a Chinese-determined system? If so, would that process be violent or peaceful, perhaps featuring some kind of recreation of the old European "pentarchy" (five-power supremacy) on a global scale?

That last thought strikes me as too mechanistic, especially now that a second major war is ongoing in the Middle East. Hamas's atrocities in Israel on October 7 show how long-simmering territorial conflicts can explode when more modern, contingent geopolitical conditions change. The Israeli-Palestinian conflict isn't new; it dates to the time of the British Empire and World War I. But without a stable geopolitical framework, such conflicts become ideally suited for covert instrumentalization by others vying for global or regional power.

Israel is now in Gaza because it now feels compelled to root out a terrorist organization that has long received support from Iran, its regional nemesis. At the same time, the US has dispatched two aircraft carrier groups to the eastern Mediterranean to prevent the war from expanding into Lebanon, where Hezbollah, another Iranian proxy, has been harassing Israel by launching drones and firing missiles across the border. The fuse that Hamas lit on October 7 is far from being extinguished.

Add in China's increasingly aggressive rhetoric toward Taiwan and its claim of sovereignty in the South China Sea, and it is easy to see how volatile the global situation is. Compounding the uncertainty, the world is undergoing a broad realignment. The Global South is demanding more seats at the table, and new alliances and coalitions are emerging beyond the reach of the West.

Will a contest of "the West against the rest" become the context in which Western dominance declines? Or will powerful political currents in Europe and the US pull the West away from its traditional alliance structures and in a more anti-democratic direction? Putin is betting on the US abandoning its transatlantic obligations after next year's presidential election. Should that happen, one shudders to think what will become of Europe.

A new world is indeed emerging. It will be characterized not only by more interdependencies, but also by more insecurity, danger, and war. Stability in international relations will become a foreign concept from a bygone age - one that we did not fully appreciate until it was gone.

From Project Syndicate