The most critical question surrounding the withdrawal of U.S. forces from Iraq is Iraq’s internal security and stability. Although the withdrawal plan approved by President Barack Obama is designed to coincide with Iraq’s ability to maintain its own stability and security, the end of U.S. military occupation is a watershed that may alter the strategies of the main Iraqi political actors, each of whom commands enough armed power to be able to shatter Iraq’s domestic peace. Should any of the main opposition groups—frustrated Sunnis, autonomy-minded Kurds, militant Shi’as—turn to force, U.S. interests and personnel could be harmed. For...

By every measure, Iraq has become more secure and stable since its paroxysm of violence in 2006–2007. Yet, simply to extrapolate this progress into the future could cause serious mistakes in U.S. assessments, policies, and plans. Take the recent trend of Sunni acceptance of Iraq’s post-Saddam political order, for example: The persistent Sunni grievances and formidable fighting capabilities outside of state control perpetuate a danger of renewed armed struggle triggered by Sunni-extremist terror, government mistreatment, or the departure of U.S. troops from Sunni-Shi’a–contested areas. Iraq remains both complex and fluid: The interaction of political groups still suspicious of...

The ISF are approaching their planned end strength of approximately 650,000 in the Arab part of Iraq, which, to us, seems ample. The numerical balance between Iraqi military forces and police forces seems reasonable. However, the quality of the ISF is very uneven: Some elements, e.g., Iraqi Special Operations Force, are well trained, disciplined, and capable; others, e.g., much of the Facility Protection Service (FPS), are ill trained and ill equipped.

The ISF consist of the army, air force, and navy (under the MoD) and the IPS, FP, border police, and FPS (under the MoI). The Counterterrorism Bureau (CTB) reports...