From the Summary: "The major challenges to coalition forces are now quelling a persistent Iraqi resistance movement and training sufficient Iraqi forces to assume responsibility for the nations domestic security. Though initially denying that there was an organized resistance movement, DOD officials have now acknowledged there is regional/local organization, with apparently ample supplies of arms and funding. CENTCOM has characterized the Iraqi resistance as 'a classical guerrilla-type campaign.' DOD initially believed the resistance to consist primarily of former regime supporters and foreign fighters; however, it has now acknowledged that growing resentment of coalition forces and an increase in sectarian conflicts, independent of connections with the earlier regime, are contributing to the insurgency. Counterinsurgency operations are being intensified in Baghdad and al-Anbar province, focusing on 'clear, hold, and build' strategy. According to DOD, as of January 1, 2007, 3,004 U.S. troops had died in Iraq operations. There have been more than 22,500 U.S. personnel wounded or injured since military operations began. Non-U.S. Coalition fatalities have totaled 250, while Iraqi security force fatalities from June 2003 through December 2006 are estimated to be 5,952."
CRS Report for Congress, RL31701