You preface your ruminations about sundry comparisons between Afghanistan and Vietnam with a few words about insurgency (“From Saigon to Kabul,” October 3, 2009). “Perhaps the best description of insurgency is War of the Flea, the title of a 1965 book on revolutionary warfare by Robert Taber, an American who witnessed Fidel Castro’s success in Cuba.” You quote his own rendering of “the dog’s disadvantages”: “too much to defend; too small, ubiquitous, and agile an enemy to come to grips with.” So far, so good. “In the end,” you conclude, “exhausted, the dog dies or gives up the fight.” Well, no dog has ever died from an attack of fleas except if they have been infected by deadly germs, as well. Besides, no dog has ever given up the fight by leaving the fleas behind. That is not an option, anyhow. Simply put, Taber’s analogy is deeply flawed. If anything, it describes how the American army understands insurgency. In that sense at least, Afghanistan and Vietnam are indeed pretty similar in spite of their many differences. The dog will forever misunderstand the fleas.