The slaughter of Parisians on November 13 was an act of war. The coordinated attacks, for which Islamic State has claimed responsibility, refute the notion that ISIS had been “contained” — the term Barack Obama used in a TV interview, just a few hours before the bombings and shootings began. Hardly the first time our president has understated the problem. Moreover, by carrying out attacks in the heart of Europe, far from its quasi-state in the Middle East, ISIS has upended the premise that it is mainly a regional menace. But the failure to understand the group runs deeper than just its military-operational capability.

Fundamental to the group’s appeal and burgeoning ambition is its claim to be advancing a (perverse) moral ideal. Islamic State is a leading faction within a broader movement, Islamic totalitarianism. That movement — encompassing Al Qaeda, Hamas, Hezbollah, Iran, among others — is united by the Islamic religious goal of conquest and domination. Adherents believe that Allah’s word must dominate every facet of an individual’s life — and all of mankind. Merely subjugating the people in one corner of the globe can hardly suffice; the righteous must act to ensure that people obey Allah alone, everywhere. For the jihadist, no act of savagery can be ruled out as immoral, so long as it is done in the path of Allah. The killers in Paris, like so many before them, were enforcing their understanding of Islamic religious doctrine, punishing unbelievers in a city of impiety.

We could have defeated this menace, long ago. We still can.

The president of France, Francois Hollande, has promised to destroy Islamic State. I hope he means it. That would be a good first step, but it cannot be the only step. To end the jihadist menace requires that we demonstrate to its followers that their cause is hopeless.

In my book, Winning the Unwinnable WarI outline what that looks like. We need to recognize the many ways our policy approach, prior to 9/11 and since then, has been self-sacrificial and incoherent. Our failure to stamp out this movement — to say nothing of the policies that empowered it — has encouraged followers to imagine their vision is, somehow, realizable. But by taking the necessary steps, we can defeat the jihadist movement.