Three years ago, in a major address at the National Defense University, President Obama announced that he had signed a classified document to tighten and formalize the rules relating to the use of lethal force against suspected terrorists “outside the United States and areas of actual hostilities.” The document — the Presidential Policy Guidance, or PPG — was not published at the time, but a redacted version of it is likely to be disclosed in the next week or so, perhaps alongside several related documents, a new executive order, and official casualty statistics for the drone war.