The lesson of the post WWII era is that if we aren’t willing to CRUSH a people like we did German and Japan, and completely control them for at least a generation while totally rebuilding their political and even to some extent social mores, then we ought to stay out of the post-conflict nation-building game.
Starting out a war against an ideology while proclaiming it “peaceful and friendly” was a loser from the beginning, it is plain to see now.
There is no way we are going to crush islam, a “Japan level” occupation is not realistic, and that only worked after the Emperor called for total surrender and compliance. The islamic threat will remain until the source is extirpated.