Even those of us who disliked Trump were deeply appreciative when he bombed Iran’s nuclear facilities. And we’ve certainly been grateful for his standing with Israel against our enemies. People respected him for being able to say things straight and do the right thing even when it was politically unpopular.

And yet now we see Trump giving a warm endorsement to none other than Zohran Mamdani. This is the man who built his entire activist career on attacking Israel, the mayor-elect who just condemn...