A safe zone in Syria would be a forward step in the Islamic State fight

"The government of President Recep Tayyip Erdogan has been pressing for a more ambitious strategy, including a no-fly zone that would extend to Aleppo. That would be a much heavier blow to the Assad regime; it would entrench the moderate opposition in the country’s second-largest city and could force the serious negotiations about a post-Assad government that the Obama administration says it seeks."