When Mayor Pete Buttigieg talks about his military service, his opponents fall silent, the media fall in love, and his political prospects soar. Veterans roll their eyes.

CNN’s Jake Tapper asked Mr. Buttigieg Sunday if President Trump “deserves some credit” for the strike that killed Iranian Maj. Gen. Qasem Soleimani. “No,” the candidate replied, “not until we know whether this was a good decision and how this decision was made.” He questioned whether “it was the right strategic move” and said his own judgment “is informed...