The 633-word statement of President Donald Trump on the Saudi royals' role in the grisly murder of Washington Post contributor Jamal Khashoggi is a remarkable document, not only for its ice-cold candor. The president re-raises a question that has roiled the nation since Jimmy Carter: To what degree should we allow idealistic values trump vital interests in determining foreign policy? On the matter of who ordered the killing of Khashoggi, Trump does not rule out the crown prince as prime suspect: "King Salman and Crown Prince Mohammad bin Salman vigorously deny any knowledge of the planning or execution of the...