How to Make the Islamic State’s Defeat Last

After months of tough urban combat, Iraqi Prime Minister Haider al-Abadi declared victory Monday over the Islamic State in its last strategic stronghold in Iraq. Iraqis celebrated in the streets, and Americans should cheer as well.

The liberation of Mosul and the inevitable, approaching liberation of Raqqa in Syria will not be the end of the Islamic State and its evil ideology. But they crush the group’s pretense to having an actual “state” based upon it. As its surviving leaders scurry to the corners of the desert, no longer can they claim to head a winning movement. Their defeat diminishes the inspiration for violent extremists, or simply lost souls on social media, to attack Americans and our friends. This is a necessary step forward in combating terrorism. Americans are safer for it.

The credit for liberating Mosul should go to the brave Iraqi forces who carried out the fight, as well as to the Kurdish peshmerga forces. But credit is also due to the superb execution by U.S. and coalition forces of the military campaign plan to train, equip and enable Iraqi security forces put in motion more than a year ago.