HARI SREENIVASAN:

The French government said today its analysis of samples from a chemical attack in Syria earlier this month prove that the government of Bashar al-Assad was responsible.

That attack was one more flash point in a war that has now entered its seventh year, and it is the subject of a searing new documentary called "Hell on Earth: The Fall of Syria and the Rise of ISIS."

It debuts at the Tribeca Film Festival this week here in New York, and will air later this summer on National Geographic.

It is co-directed by the journalist and author Sebastian Junger, who also narrates the film.

Thanks for joining us.

SEBASTIAN JUNGER, Co-Director, "Hell on Earth: The Fall of Syria and the Rise of ISIS": Thank you.