Early Monday morning, when much of the White House press corps was fast asleep, President Donald Trump demanded the federal government conduct a “major investigation” into singer-songwriter Bruce Springsteen, a Trump critic, and his presidential endorsement last year.

On Friday, the sitting American president had already warned Springsteen that he “ought to Keep His Mouth Shut,” and “we’ll all see how it goes for him” once the rock star is back home in the United States. Springsteen failed to comply, and spoke out once again about the “unfit” president at a concert in Manchester,...