A few years ago, I found myself in Amsterdam watching the French intellectual Bernard-Henri Lévy debate Russian intellectual Aleksandr Dugin on the subject of American hegemony and the global order. Before an ambivalent audience at this public symposium, Lévy began with a rousing defense of the liberal creed. Dugin, whose philosophy supports Moscow’s aggressive foreign policy, submitted that liberalism was a species of “totalitarianism.”

The battle of ideas intensified when the subject turned to Ukraine. Dugin argued vociferously in favor of Russia’s 2014 invasion and annexation, on the theory that Ukraine was the cradle of Russian civilization and thus within Russia’s sphere of interest. The only criticism he made of Russian policy was that, by limiting its military occupation to Crimea and the Donbass, it had not gone far enough. To Dugin’s mind, the Kremlin ought to have seized Novorossiya—a territorial expanse home to Ukraine’s Russian speakers—in its entirety and reconstructed what remained of Ukraine as a buffer state. Lévy suggested this “philosophy of war” would turn Ukraine into a battleground to defend the security architecture of the free world. Eight years later, events have demonstrated the prescience of that declaration.

Now Lévy has released a documentary, Pourquoi l’Ukraine, whose New York premiere was screened last month at the United Nations. Elegantly narrated in Lévy’s native French, Why Ukraine tells the story of the Russian invasion that commenced on February 24 of this year and continues to wreak havoc on that country. It is a poignant depiction of how thin is the barrier of civilization that protects humanity from barbarism.

Lévy has a knack for inserting himself into the center of revolutionary situations—a habit he honed to great effect in Libya, where his activism during the 2011 uprising helped encourage Western military intervention. This time, the bell has tolled in Ukraine. Whether donning a flak jacket or his trademark black suit, he looks equally comfortable in frontline trenches near Kharkiv as in Kyiv’s government quarter. In this way, the film reaches the bottom of the society and the top of the state. In dialogue with the most endangered commander-in-chief on earth and embedded with platoons of citizen soldiers, Lévy shows that Ukrainians “know why they fight.”

The documentary begins with Lévy and his film crew landing in the western Ukrainian city of Lviv during the opening salvos of Vladimir Putin’s unprovoked war. In these hours when Ukraine was “holding its breath,” humanitarian outfits and war correspondents joined Russian armored convoys by crossing into Ukrainian territory. Ukrainians and foreign poohbahs, meantime, were flocking in the opposite direction, hoping to escape Russia’s advance.

After preliminary scenes of Russia’s initial plan of battle, the film casts a backward glance at the events that preceded it. Lévy describes the cruel Putin dictatorship and its aggressive designs upon its Ukrainian neighbor. The story comes into focus in the winter of 2014, when Ukrainians in Kyiv’s Maidan rallied to overthrow their corrupt Russian-backed president, Viktor Yanukovych, after he thwarted popular measures to enhance European integration.

This revolution struck Lévy, who was on hand to address and encourage the protestors, as a stirring blend of the 1968 student demonstrations and the storming of the Bastille. At the podium he gave tribute to Ukrainians for being “the guardians of democracy” and “the guardians of Europe.” After lauding Ukrainians’ brave stand, he confesses to having a “heavy heart” in light of Putin’s equal and opposite will to domination. Ever since, Lévy’s stake in this contest has ensured that, regardless of his location, he has “lived on Ukrainian time.”

That clash prefigured the present struggle between the “champions of freedom” and a fascistic “cult of death,” personified by Putin’s KGB mentality. The enormity of the violence and terror already inflicted on Ukraine is hard to quantify, but it is to Lévy’s credit that he mustered the energy to expose it to the world.

The highly candid and affecting film returns to the ongoing conflict and the spectacle of an entire society mobilized for war. It recycles some by-now-familiar aerial scenes of columns of Russian armor being pulverized by a combination of Ukrainian artillery fire and drone strikes. But it also sheds light on Russia’s brutal way of war. Ukrainians viscerally understand that they are confronting an army that can only “bomb and destroy,” as Lévy says. Traditional Russian military doctrine stresses mass fire systems to crush the enemy’s will and ignores the distinction between combatants and noncombatants; Ukraine testifies to the hideous results of this brand of combat.

Shouts of Slava Ukraini! (“Glory to Ukraine!”) resound throughout the film, which might have caused U.N. bureaucrats at the premiere to wince in embarrassment but seem altogether fitting for a people in existential peril. As the scene shifts between subterranean military bases and sandbagged urban streets lined with what Ukrainians call “block posts” manned by armed civilians in Territorial Defense units, the lesson is pounded home: in war, as Napoleon claimed, “the moral is to the physical as three is to one.” Lévy updates this old martial wisdom: “The valor of an army is shown more by the spirit of its fighters than by the strength of its weapons.” Ukrainian forces have proved that pairing fighting spirit with the High Mobility Artillery Rocket System makes for a winning combination.

Though Lévy blames Putin as the proximate cause of the war, he doesn’t linger on the villains to the exclusion of the heroes. He plainly stands in awe of Volodymyr Zelensky, whom he met before the war. Zelensky and his cabinet have since come to embody masculine virtues in the modern age for facing down immense odds against surviving—let alone winning—this war. Remaining in Kyiv while Russian forces raced toward the Ukrainian capital at the outset of the war, the comedian-turned-president rejected a U.S. offer of evacuation with the famous line, “I need ammunition, not a taxi.” (“A sublime reply worthy of Plutarch’s legendary figures,” exclaims Lévy.)

We know already that the war in Ukraine has smothered the post–Cold War settlement. The era that opened with hopeful proclamations by Boris Yeltsin that post-Soviet Russia would be an integral part of a “Greater Europe” and would be invested in a new order “in which no single state will be able to impose its will on any other” has run its course. And the war has proved that Europe’s national borders are not set in stone.

This outcome was not predetermined. The strategic incoherence of the Atlantic alliance before 2014 helped create the conditions for this war. The West’s hesitancy after 2014 permitted the balance of power to shift in Putin’s favor. Small but significant factions in both political parties resent America’s role as the arsenal of Ukrainian democracy and seem ready to abandon the country.

But singular culpability rests with the ex-KGB officer in the Kremlin who has reduced Ukraine to a landscape of misery and ruin while making Russia a pariah. Whatever else happens, Putin’s abiding legacy will be the moral disgrace and material devastation wrought by his “special military operation.” In this new and dangerous epoch, Lévy’s film will be a useful guide to understanding the struggle raging on the edge of Europe.