Just a few days ago, we passed a forlorn milestone: six months of the presidency of Donald Trump. On every front, this first six months has been a disaster. Trump humiliates America on the international stage, and at home he continues to head a dysfunctional government, presiding by tweet, and with scandal swirling ever closer around him. On Guantánamo, as we have repeatedly noted, he has done very little. His initial threats to send new prisoners there, and to revive CIA "black sites," have not materialized. However, if he has not opened the door to new arrivals, he has certainly closed the...