No need to build to a crescendo — let’s just say it: The Trump-Russia investigation was a politically driven fraud from beginning to end. It was opened on false pretenses, sustained by investigative abuses, and will undoubtedly end in recriminatory angst, which is what happens when the kind of accountability the victims demand does not, indeed cannot, come to pass. Worst of all is the damage wrought, though even that isn’t fully understood. Obama administration officials exploited the awesome national security powers that we trust our government to use for counterintelligence operations that safeguard America from jihadists and other foreign hostiles. Because of the abuse, and the growing awareness that few of the abusers will be held to meaningful account, those powers have lost the solid constituency they had maintained in Congress for nearly two decades. Thus, this episode will prove to be a catastrophe for American national security. Last August, I released Ball of Collusion. As a former longtime federal law enforcement official who is proud of that service, I had come reluctantly to the realization that the Trump-Russia escapade was less an investigation than a political narrative — hence the book’s subtitle, The Plot to Rig an Election and Destroy a Presidency. In fact, it would be more accurate to say I had been dragged to it, kicking and screaming. In the early days, friends of mine, both pro-Trump and Trump-skeptic, asked me...