“When the full extent of your venality, moral turpitude, and political corruption becomes known,” read former CIA Director John Brennan’s melodramatic warning to President Trump, “you will take your rightful place as a disgraced demagogue in the dustbin of history.” Brennan sought to convey his righteous confidence in history’s inevitable verdict on the Trump administration, but his hollow posturing is betrayed by how he and the rest of the Obama administration-in-exile have never stopped trying to influence the jury. Well in excess of their predecessors, the last administration’s chief national security and foreign policy officials have spent their years in the wilderness aggressively inserting themselves into the national conversation. They are ubiquitous fixtures on cable news, regular features on the nation’s op-ed pages, and have even formed a rapid response organization dedicated, in the words...