The speed of the news cycle and the media obsession with the presidential horseraces have crowded out a crucial development in the war on ISIS and related Islamic jihadist groups. House Speaker Paul Ryan has been sounding out colleagues for a new Authorization for Use of Military Force (AUMF). The current AUMF, which was written in 2001 and targeted groups connected to 9/11, has not been renewed. Believe it or not. Bravo for Paul Ryan's statesmanship. But a new AUMF must be accompanied by a clear U.S. declaration of war against ISIS. We will never destroy them without a full-blown...