President Nicolás Maduro of Venezuela is an exuberant dictator, a lover of military salutes who is being investigated for crimes against humanity, but he’s not reckless enough to invade neighboring Guyana, is he? Would the leader of a country in an ever-deepening economic crisis risk starting Latin America’s first interstate war this century? Well, maybe. For a century and a half, Guyana and Venezuela have quarreled over Essequibo, a stretch of the Amazon that both countries claim. Guyana has long governed the territory, but Venezuela also claims sovereignty over it, citing maps drawn in colonial times. Last year, Maduro expressed...