In the wake of the U.S. withdrawal, a resurgent al-Qaeda in Iraq, allied with jihadist fighters in neighboring Syria, constitutes a considerable threat to regional security, explains this Backgrounder.

Iraq's provincial elections provide signals about the maturity of the country's political system, as well as highlight new power brokers in the provinces.

The Sunni awakening movement and the Sons of Iraq security forces it inspired helped restore peace. Iraq's long-term stability could hinge on keeping the movement satiated, experts say.

Iraqi lawmakers approved new ground rules for the U.S. troop presence, including a U.S. withdrawal by 2011. But questions about the accords' legal longevity remain.

The anti-American cleric Muqtada al-Sadr, virtually unknown before the collapse of Saddam Hussein's government, has leveraged his family name to become one of the most influential Shiite leaders in modern-day Iraq.

The division of Iraq’s oil wealth is an important obstacle to a power-sharing deal. At issue is whether revenues should be regionally or centrally controlled.

Estimates of the total long-term economic costs of the Iraq and Afghanistan wars vary wildly and remain hotly disputed among experts.

Western efforts to rebuild Iraq have focused on military and political progress but revival of civilian infrastructure lags badly.

While the American public focuses on bringing U.S. forces home from Iraq and Afghanistan, defense planners in Washington consider what to do with them when they get back.

A Senate proposal calling for the restructuring of Iraq’s government has drawn fire from Iraqis who liken it to partition. Amid the criticism have emerged other controversial options.

Advocating for greater Kurdish autonomy through violent resistance, the Kurdistan Workers Party remains a vibrant militant presence on the border of northern Iraq and southern Turkey.

Gen. David Petraeus’ assertions about falling casualties in Iraq are supported by a range of objective sources. But his testimony to Congress does not establish whether the decline is attributable to the surge or to sectarian cleansing.

The U.S. Army is reorganizing to create smaller, more mobile units without sacrificing firepower. Some experts, however, wonder whether that aim addresses the lessons of Iraq.

The U.S. military’s methodology for measuring violence in Iraq draws criticism from some quarters. The Pentagon concedes some kinds of violence don’t get included, but insists its consistent application of these methods results in an accurate plotting of trends.

Hundreds of thousands of Iraqi security personnel have received U.S.-led counterinsurgency training. But big questions remain over their readiness to replace U.S. forces.

Experts point to a number of postwar models, from Bosnia to Vietnam to South Korea, for Iraq to follow once U.S. forces leave.

Iraq’s failing economy helps feed the cycle of violence there. Beyond restoring security, however, experts disagree over how to resuscitate it.

Despite eroding public support for the Iraq war, troop morale remains high. Experts warn that could change as U.S. forces get further bogged down in Iraq.

Some U.S. analysts recommend a national ID database with biometric cards to identify insurgents in Iraq, but the proposal faces resistance from the U.S. military.