Aleppo is often invoked as a symbol of the U.S. and the world's failure in Syria. President Obama, in particular, takes a lot of the blame for failing to intervene to stop the country's civil war, in which nearly half a million people have been killed.

Here & Now's Robin Young looks back at Obama's Syria policy — and what might have been done differently — with Joshua Landis (@joshua_landis), director of the Center for Middle East Studies at the University of Oklahoma.