Since former President George W. Bush’s infamous “mission accomplished” moment celebrating what some viewed as defeat of Islamic terrorism, Americans have learned to our dismay that wiping out the scourge will not be easy.

Another reminder of that was received this week, from Iraqi forces fighting to retake Mosul from Islamic State terrorists.

For weeks, Iraqi officials have sounded optimistic about the battle for Mosul, which is Iraq’s second-largest city. On Monday, they came very close to their own “mission accomplished” outlook, as Iraqi troops seemed to have taken Mosul’s center.

But by Tuesday, those troops were retreating in disorder. What they thought was an easy fight turned into an ISIS ambush.

President Donald Trump has promised he has a plan to destroy ISIS and other terrorist groups. Let us hope his confidence is not misplaced. Clearly, a campaign not to defeat the murderers — but instead, to destroy them — needs to be mounted.