Signs the United States may strike Islamic State militants in their Syrian stronghold reveal a shift in the politics of foreign war in Washington, after the trauma of the post-Iraq era. A year ago, President Barack Obama was set to bomb Syria -- but balked at the last minute after sizing up beckoning political isolation in his war-weary nation. The execution of captive US journalist James Foley and the fear an IS caliphate could become a terror haven have challenged an administration foreign policy built on the conceit that the "tide of war is receding." Obama has made ** effort to hide his antipathy to open-ended engagements in the Middle East, despite potent but limited campaigns against Al-Qaeda in Pakistan and in Libya.