Every isolationist American politician who would turn his back on the Ukrainians should be made to watch “Glory to the Heroes,” a film by Bernard-Henri Lévy that premieres in New York on Wednesday. The film highlights the valor of Ukraine’s soldiers, as well as the crimes of a Russian army that has raped, tortured and murdered civilians, blown up a dam, and bombed apartment blocks, churches and schools.

The documentary is Mr. Lévy’s third on the Ukraine war, all co-directed with Marc Roussel. The first and second were “Why Ukraine” (2022) and “Slava Ukraini” (2023), the latter title a patriotic salute that means “Glory to Ukraine.” He prays he won’t have to make a fourth. For that would mean the Ukrainians haven’t won the war, and that his mission to ensure the world pays heed to Ukraine, “that it doesn’t switch off,” is still unfinished. “I hope this is the last film,” Mr. Lévy says in an interview in his Paris apartment, “but it depends on Biden.”

It depends on Congress, too, which is squabbling over how much aid to give Kyiv, or whether to give it at all. The “magnificent Ukrainians,” Mr. Lévy says, “do the best they can. They cannot do more. They cannot shed more blood. They cannot show more bravery. They cannot have higher morale. They are at the maximum.” He is unabashed in expressing his “love and admiration for these people.” They are “heroic, chivalrous, like knights on Europe’s front line.” What is missing is game-changing support, which must come from America.

When the history of the Ukrainian war is written one day—God willing, by victorious Ukrainians—there will be a grateful paean to Mr. Lévy, a 75-year-old French philosopher who has made the war his righteous obsession. He has traveled to Ukraine 12 times since Vladimir Putin invaded in February 2022, and he doesn’t simply park himself in the capital. He ventures almost always to the front lines at personal peril, taking risks that he, a wealthy author renowned in France, has no need to face. He embeds with Ukrainian troops—“eating what they eat, sleeping where they sleep”—and reports on the combat, highlighting how they have been more than a match for the vaunted Russian army.

In startling footage, Mr. Lévy’s film shows interviews with captured Russian soldiers, non-Slavic conscripts sent to fight with no military training. One prisoner says he was released from jail by the Russian Defense Ministry on condition that he go to Ukraine. He was told he would be an auxiliary but was sent to the front lines. Surrendering was a no-brainer, the only way to escape certain death in an unequal battle against war-hardened Ukrainian soldiers.

Mr. Lévy would like Russian citizens to watch his film and is working on ways—which he won’t disclose—to make it available to stream in Russia. With this film, he says, “they will see the truth face to face. The movie is a terrible condemnation for them, of what they’ve done in Ukraine, of the mediocrity of their army. They should be ashamed.”

But not all Russian soldiers are feckless conscripts, and the Ukrainians are at a stalemate. “We haven’t provided what we promised,” Mr. Lévy says of the West. “If Ukraine does not win, it will be a disaster for the whole world. If Putin wins in Ukraine, China will attack Taiwan.” Mr. Lévy laments in his film, which he narrates, that “we provide enough weapons for the Ukrainians not to lose, but not enough for the Ukrainians to win.” He calls this “a sort of devilish, diabolic calculation. It’s not consciously made, of course, but the dosage is exactly what’s necessary to hold the line, but not to advance.”

Mr. Lévy acknowledges that his is “a partisan film, committed and passionate. I take sides.” He marvels at the morale of Ukrainians. “When your very existence is at stake, you have no choice.” And so their resolve, their spirit, is a form of self-protection. The Ukrainians also have “great values,” he adds. “You can see if a people are great or not by the way they react when they face annihilation—of their culture, their identity, their children.”

To watch the Ukrainians fight back against the Russians has been a “revelation” for Mr. Lévy, and his films are a tribute to their martial will to survive. He contrasts this—he’s “sad to say”—with the record of his own countrymen in World War II. “Eighty-five years ago the French were facing their own existential threats. And except for a few, they did not behave so well.” If Ukraine had behaved like France, he says, “the war would be over.” Slava Ukraini!

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