After six years in office, Obama broadcasts his world-weariness with wan gestures and pauses, with loose moments in the White House press room. The world has stubbornly denied him his ambition to transcend its cruelties, pivot smartly to the East, and “do some nation-building here at home.” Obama’s halting cool at the lectern now reads too often as weakness, and when he protests against the charges of weakness he can seem just tired. As the Middle East disintegrates and a vengeful cynic in the Kremlin invades his neighbor, Obama has offered no full and clarifying foreign-policy vision.