John Hagan, Joshua Kaiser, and Anna Hanson; Jon R. Lindsay and Austin G. Long respond to Stephen Biddle, Jeffrey A. Friedman, and Jacob N. Shapiro's summer 2012 International Security article, "Testing the Surge: Why Did Violence Decline in Iraq in 2007?"

Why did violence decline in Iraq in 2007? Many credit the "surge," or the program of U.S. reinforcements and doctrinal changes that began in January 2007. Others cite the voluntary insurgent stand-downs of the Sunni Awakening or say that the violence had simply run its course after a wave of sectarian cleansing. Evidence drawn from recently declassified data on violence at local levels and a series of seventy structured interviews with coalition participants finds little support for the cleansing or Awakening theses. This analysis constitutes the first attempt to gather systematic evidence across space and time to help resolve this debate, and it shows that a synergistic interaction between the surge and the Awakening was required for violence to drop as quickly and widely as it did.

Why did violence decline in Iraq in 2007? A new analysis suggests that a synergistic interaction between the surge and the Awakening caused the significant drop in violence, creating a set of circumstances that neither could have achieved alone.