The war with Iran has been marked by collapsed ceasefires, expanding airstrikes and mounting American and Iranian casualties. In recent days the U.S. military announced the deaths of three more servicemembers, two of whom died in an Iranian missile strike. The U.S. is pressing on with a fight that has no end in sight — or even a clear definition of what an acceptable end would be. BEIRUT — President Trump long railed against forever wars. For years, whether as president or candidate, he flayed electoral opponents and previous presidents with his signature barbs, calling their entanglements a “complete waste...