President Trump promised voters during his campaign for a second term that he had bigger things on his mind than retribution against opponents. But it is increasingly clear that vengeance is a large part, maybe the largest part, of how he will define success in his second term. His revenge campaign took an ominous turn Friday as FBI agents raided the home and office of Mr. Trump’s first-term national security adviser John Bolton. They brought two broad warrants to search the “premises.” Agents showed up unannounced at his Bethesda, Md., home at 7 a.m. They confiscated his wife Gretchen’s phone...