Donald Trump is famous for describing his many opponents—from Rosie O’Donnell to an astrologer in Cleveland named Gary—as “losers.” But on Tuesday, following a terrorist attack that killed at least 22 people at a concert in the English city of Manchester, the American president did something new and notable: He applied the term to those who have claimed responsibility for detonating a bomb among teenagers who had gathered to watch Ariana Grande perform—an act for which ISIS has taken credit.

“So many young, beautiful, innocent people living and enjoying their lives murdered by evil losers in life,” Trump said during a visit to Israel. “I won’t call them monsters because they would like that term. They would think that’s a great name. I will call them from now on losers because that’s what they are. They’re losers. And we’ll have more of them. But they’re losers—just remember that.”

It’s a jarring term to use—a schoolyard put-down that Trump has favored in one petty context after another, uttered at a moment when young lives have been cut short and life’s simple joys have been brutally disrupted.

But it’s also a compelling strategy. Barack Obama refused to use phrases like “the Islamic State” and “radical Islamic terrorism” in part because he wanted to deny ISIS and its ilk a critical asset: religious legitimacy. Trump, who long condemned Obama for this position, didn’t just back away on Tuesday from the “radical Islam” language he deployed so often during the presidential campaign and the early days of his presidency. Echoing his recent speech in Saudi Arabia on jihadist terrorism, Trump used an epithet that translates across religions: “evil.” (Trump is also echoing George W. Bush, who described his war on terror as a battle between good and evil, and Ronald Reagan, who spoke of a moral struggle between the freedom-loving United States and the “Evil Empire” in Russia.) And he sought to deprive ISIS of another core asset: the perception that it is winning.

As my colleague Graeme Wood has written, one of the best of bad options for fighting ISIS is to “slowly bleed it” of territory, revenue, recruits, and other sources of strength. “[W]ith every month that [the Islamic State] fails to expand, it resembles less the conquering state of the Prophet Muhammad than yet another Middle Eastern government failing to bring prosperity to its people,” he noted. “As it stagnates or slowly shrinks, its claim that it is the engine of God’s will and the agent of apocalypse will weaken, and fewer believers will arrive. And as more reports of misery within it leak out, radical Islamist movements elsewhere will be discredited.”

This contest is playing out not just in the physical world, but in the world of ideas. In an article for The Atlantic on ISIS’s countercultural appeal to some Muslims in the West—an appeal he characterizes as “jihadi cool”—Simon Cottee quotes a supporter of the group, who writes, “The bottom line is that the Islamic State is the classic sci-fi underdog battling a seemingly all powerful Evil Empire America against impossible odds—and in the very best sci-fi tradition—they are winning.” In the wake of the Manchester attack, Trump contradicted that narrative. It’s an approach perfectly suited to a man who has spent a lifetime dividing the world into winners and losers. And in this case, it may well be the right one.