If it becomes reasonably clear that the Assad regime was responsible for today’s apparent chemical strikes, nothing less than direct military action will alter its calculus or prevent further massacres.

Based on extensive video, photo, and eyewitness accounts, it seems clear that something major and terrible happened today in Syria. Thousands of people were reportedly killed or wounded, nearly all in the Damascus vicinity. No previous action by the regime or the opposition has produced casualties on this scale or in this geographical concentration. This appears to have been a calculated act, likely intended to change the military situation around the capital in a decisive way. It also coincides with the anniversaries of two ineffectual U.S. policy pronouncements: President Obama’s August 18, 2011, declaration that Bashar al-Assad must “step aside,” and his August 20, 2012, statement that the use of chemical weapons (CW) would be a game changer.