New Year’s terror in New Orleans: 14 people dead and dozens wounded after a 42-year-old man drove a rented pickup into a celebratory crowd on Bourbon Street. Police killed the terrorist in a shootout before he could wreak further havoc. The truck bore an ISIS flag, the banner of the global jihad. In a cruel irony, revelers had gathered to welcome a new beginning. The attack was a horrible reminder of ancient evils and enduring threats.

At such moments our attention turns inward. The media provide updates, profile victims, and explore how the assailant, U.S. citizen and Army veteran Shamsud-Din Jabbar of Houston, Texas, became a radical Islamist. It’s tempting to fixate on Jabbar’s crooked path to mass murder while neglecting the broader movement to which he belonged. Such temptations should be avoided. What happened in New Orleans was larger than one man’s pathology. It was the latest atrocity committed in the name of a sick ideology.

The jihadist worldview exemplified by ISIS has not been vanquished. On the contrary: It is resurgent. There was a terrible attack in Moscow last April, and last month’s Christmas market attack in Germany killed four women and a nine-year-old boy. Radical Islamism is growing in and fuels violence throughout Africa. ISIS rages in Syria and Iraq as its Sunni compatriots in Hamas fight to the death in Gaza. Shiite radicals in Hezbollah and among the Houthis sow terror at the direction of their Iranian masters. Above all, ISIS has embedded in Afghanistan, where its leaders issue communiques to an international following, plot against the West, and attack both the Taliban government and neighboring Pakistan.

Even a “virtual” caliphate such as ISIS has a physical infrastructure: fortresses, hideouts, safe houses, networks, and members. The strength of the material base has a direct relationship with the ideology’s global appeal. This is not idle speculation. It is historical fact. America’s global war on terror decimated al Qaeda. The surge defeated al Qaeda in Iraq. The anti-ISIS campaign initiated reluctantly under President Obama and intensified righteously by President Trump brought the group to its knees in Iraq and Syria. Israel’s response to the October 7 attacks has crushed Hamas, hobbled Hezbollah, and left Iran scurrying for an escape hatch.

Terrorist movements wax strong when they believe that history is on their side. And there is no better way to rid the terrorists of that notion than to deny them haven and reduce their leaders to ash.

America forgot this lesson. Our leaders reduced commitments in Iraq and Syria. Federal law enforcement shifted its attention to domestic extremism and white nationalism. Worst of all, President Biden beat a hasty retreat from Afghanistan that left 13 U.S. servicemen killed, U.S. citizens and visa-holders stranded, Afghan allies abandoned, the Afghan people in hock to a jihadist militia that calls itself a government, and Afghanistan’s ungoverned spaces in the hands of ISIS.

At the time, Biden pledged continued surveillance of the enemy, “over-the-horizon” military capabilities, and support for Afghan women and girls. None of this was true. Retired general Frank McKenzie, former CENTCOM commander, said last spring that “in Afghanistan, we have almost no ability to see into that country and almost no ability to strike into that country.” The Taliban resumed public executions, imposed dress and behavioral codes on women, and deprived girls of schooling. The other day, the Taliban said it would shutter NGOs that employ women.

Consider the contrast between Israel and the United States. Israel possesses the will to strike its enemies, establish facts on the ground favorable to its security, and restore deterrence in a dangerous neighborhood. The United States, meanwhile, has been tossed about by a whirlwind of events that it believes are beyond its control: an open southern border, a passive-aggressive desire to renew the nuclear agreement with Iran, disaster in Afghanistan, war between Russia and Ukraine that is lessening weapons stockpiles, virulent anti-Semitism on campuses and in city streets, and long-running operations against the Houthis that have led nowhere. This aimlessness and passivity create openings for terrorists. It gives them the sense of impending victory.

I am not arguing that we re-invade Afghanistan tomorrow. Nor am I saying that a more assertive U.S. foreign policy would end every threat to the homeland. My argument is that the way to reduce the ISIS threat, foreign and domestic, is to take the fight to the evildoers. Don’t pretend jihadists can be left to their own devices. Put them on the defensive. Thin out their ranks, dry up their finances, keep them on the run. Then ISIS’s ability to inspire will wane. And justice will be done for the people of New Orleans.

Matthew Continetti is a senior fellow at the American Enterprise Institute and the founding editor of The Washington Free Beacon. For more from the Free Beacon, sign up free of charge for the Morning Beacon email.