Bashar al-Assad’s Syrian regime forces are suspected of using chemical weapons in an attack in a Damascus suburb last week. In spring 2013, allegations surfaced that the regime had used chemical agents against civilians, and similar allegations arose in December. Brookings scholars have offered analysis and commentary over the last year, since President Obama’s declaration of August 20, 2012 that any attempt by Syria to move or use its chemical weapons would be a “red line” that “would change my calculus.”