AT A MINUTE before 5 a.m. on April 27, ABC News’ James Gordon Meek fired off a tweet with a single word: “FACTS.” The network’s national-security investigative producer was responding to former CIA agent Marc Polymeropoulos’ take that the Ukrainian military — with assistance from the U.S. — was thriving against Russian forces. Polymeropoulos’ tweet — filled with acronyms indecipherable to the layperson, like “TTPs,” “UW,” and “EW” — was itself a reply to a missive from Washington Post Pentagon reporter Dan Lamothe, who noted the wealth of information the U.S. military had gathered about Russian ops by observing their...