The Atlantic published the article UN Sources Say Syrian Rebels — Not Assad — Used Sarin Gas on May 5, 2013.
Plus how in the world would the rebels even get sarin gas? It doesn’t grow on trees, and though the government does have a bunch on hand, they’ve been guarding it heavily.
Perhaps my previous post Seymour Hersh Says Hillary Approved Sending Libya’s Sarin to Syrian Rebels provides the answer to this question. What did Hillary expect the Syrian rebels would do with the Sarin?