This report provides background information for Congress on the levels of Department of Defense (DOD) military servicemembers and contractor personnel deployed in support of prior and ongoing military operations in Iraq and Afghanistan. For more information on DOD's use of contractor personnel, see CRS In Focus IF10600, Defense Primer: Department of Defense Contractors , by Heidi M. Peters and Moshe Schwartz and CRS Report R43074, Department of Defense's Use of Contractors to Support Military Operations: Background, Analysis, and Issues for Congress , by Moshe Schwartz. Throughout its history, DOD has relied on contractors to support a wide range of military operations. Operations over the past 30 years have highlighted the critical role that contractors play in supporting U.S. military servicemembers, both in terms of the number of contractors and the type of work being performed. During recent U.S. military operations in Iraq and Afghanistan, contractors frequently averaged 50% or more of the total DOD presence in-country. Since 2008, U.S. Central Command (CENTCOM) has published quarterly contractor census reports that provide aggregated data – including elements such as mission category and nationality – on contractors employed through DOD-funded contracts who are physically located within the CENTCOM area of responsibility. Analysts and observers have previously raised questions about the reliability of the data gathered by DOD regarding the number of contractors it employs in theater in support of military operations. DOD officials, however, have stated that since 2009, the DOD has implemented a variety of mechanisms to improve the reliability of contractor data it gathers, including modifications to information technology systems, such as data collection systems like the joint Synchronized Predeployment and Operational Tracker (SPOT) database; updates and changes to related departmental policies; and changes in "leadership emphasis" within DOD and the combatant commands. For the fourth quarter of Fiscal Year (FY) 2018, CENTCOM reported 49,451 contractor personnel working for DOD within its area of responsibility, which included 28,189 individuals located in Afghanistan, Iraq, and Syria (see Figure 1 and Figure 2 ). From FY2009 to FY2018, obligations for all DOD-funded contracts performed within the Iraq and Afghanistan areas of operation totaled approximately $208 billion in FY2019 dollars (see Table 5 ). Force management levels, sometimes also described as troop caps, troop ceilings, or force manning levels, have historically been used by the United States to establish bounds on the number of military personnel that may be deployed in a country or region. The executive and legislative branches of the U.S. government have used force management levels to guide the execution of certain overseas U.S. military operations, as well as the associated presence of DOD personnel. During the 1980s, for example, Congress used provisions within annual appropriations legislation to establish force management levels limiting the number of active duty U.S. military personnel stationed ashore in Europe. The Obama Administration used force management levels to manage its drawdown of the U.S. military presence in Afghanistan, and to manage the U.S. military presence in Iraq and Syria under Operation Inherent Resolve. The Trump Administration has reportedly delegated the authority to establish force management levels for Afghanistan, Iraq, and Syria to the Secretary of Defense. In August 2017, the DOD announced that it was revising its force management level accounting and reporting practices for Afghanistan to also include U.S. Armed Forces personnel in-country for short-duration missions, personnel in a temporary duty status, personnel assigned to combat support agencies, and forces assigned to the material recovery element and the Resolute Support sustainment brigade in reported totals. In late 2017, the Defense Department stopped reporting the number of U.S. military personnel deployed in support of operations in Afghanistan, Iraq, and Syria as part of its quarterly manpower reports and in other official releases. These data remain withheld, leading to criticism from some observers and Members of Congress. Some observers and experts argued that external "resource limits" of force management levels may have increased DOD's "reliance on…contractor and temporary duty personnel" to effectively execute ongoing military operations in Afghanistan, Iraq, and Syria. In February 2017, U.S. Army General John Nicholson, then Commander of the NATO Resolute Support Mission and United States Forces–Afghanistan, testified before the Senate Armed Services Committee that DOD had to "substitute contractors for soldiers in order to meet the force manning levels" in Afghanistan. While the drawdown of U.S. forces contributed to a demonstrable increase in the ratio of contractors to uniformed servicemembers in Afghanistan between 2012 and 2017, it is difficult to assess if the increased ratio supported General Nicholson's assertion. The House-passed version of the FY2018 National Defense Authorization Act (NDAA, H.R. 2810 ) contained a provision (Section 923) that would have expressed the sense of Congress that the DOD should discourage the practice of substituting contractor personnel for available members of the Armed Forces when a unit deploys overseas. This section also would have required the Secretary of Defense to provide a related briefing to the congressional defense committees. A similar provision was not included in the Senate amendment to H.R. 2810 . While the House receded in conference, the conferees directed the Secretary of Defense to provide a briefing detailing steps taken by DOD to revise deployment guidelines to ensure readiness, unit cohesion, and maintenance were prioritized, as well as the Secretary of Defense's plan to establish a policy to avoid the practice of directly substituting contractor personnel for U.S. military personnel when practicable in the future. Concern about DOD's use of contractors in contingency operations predates the recent usage of force management levels. For example, the Commission on Wartime Contracting in Iraq and Afghanistan, in its 2011 final report to Congress, expressed its view that operations in Iraq and Afghanistan between FY2002 and FY2011 had led to an "unhealthy over-reliance" on contractors by DOD, Department of State, and USAID. In Iraq and Afghanistan, armed and unarmed private security contractors have been employed to provide services such as protecting fixed locations; guarding traveling convoys; providing security escorts; and training police and military personnel. The number of private security contractor employees working for DOD in Iraq and Afghanistan has fluctuated significantly over time, and is dependent on a variety of factors, including current force management levels in-country and U.S. operational needs. The presence of private security contractors peaked in Afghanistan in 2012 at more than 28,000 individuals and in Iraq in 2009 at more than 15,000 individuals. For the fourth quarter of FY2018, DOD reported 4,172 private security contractors in Afghanistan, with 2,397 categorized as armed private security contractors (see Table 2 ). DOD reported 418 security contractor personnel in Iraq and Syria during the same period, none of whom were identified as armed private security contractors (see Table 4 ). As of the fourth quarter of FY2018, 25,239 DOD contractor personnel were located in Afghanistan (see Table 1 ). Approximately 44% of DOD's reported individual contractors were U.S. citizens (10,989), approximately 42% were third-country nationals (10,628), and roughly 14% were local nationals (3,622). Of the 25,239 DOD contractor personnel, about 9% were armed private security contractors (2,397). As of May 2019, observers and analysts estimated the number of U.S. Armed Forces personnel in Afghanistan to be between 14,000 and 15,000. Reports in early 2019 indicate the Trump Administration may be contemplating withdrawing some portion of in-country U.S. forces (a subject of ongoing U.S.-Taliban negotiations). U.S. officials have stated that no final policy decision has been made. DOD ceased publicly reporting numbers of DOD contractor personnel working in Iraq in December 2013, following the conclusion of the U.S. combat mission in Iraq (Operation Iraqi Freedom and Operation New Dawn), and the subsequent drawdown of DOD contractor personnel levels in Iraq. In late 2014, in response in part to developing operations in the region, DOD reinitiated reporting broad estimates of DOD contractor personnel deployed in Iraq in support of Operation Inherent Resolve (OIR). As the number of DOD contractor personnel in Iraq increased over the first six months of 2015, DOD resumed reporting exact numbers and primary mission categories of OIR contractor personnel in June 2015. In the second quarter of FY2018, DOD began reporting a combined total of contractor personnel physically located in Iraq and Syria. As of the fourth quarter of FY2018, there were 6,318 DOD contractor personnel in Iraq and Syria (see Table 3 ). Approximately 49% of DOD's reported individual contractors were U.S. citizens (3,086), approximately 38% were third-country nationals (2,405); and roughly 13% were local/host-country nationals. As of FY2018, CENTCOM has not resumed reporting data on DOD-funded private security personnel in Iraq. In December 2017, DOD indicated the number of U.S. Armed Forces personnel in Iraq was roughly 5,200, and indicated the number of U.S. Armed Forces personnel in Syria was approximately 2,000. In December 2018, President Donald J. Trump announced that U.S. forces had defeated the Islamic State and would leave Syria; however, in February 2019, the White House indicated that several hundred U.S. troops would remain in Syria.

Summary: Throughout its history, the Department of Defense (DOD) has relied on contractors to support a wide range of military operations. Operations over the last thirty years have highlighted the critical role that contractors play in supporting U.S. troops—both in terms of the number of contractors and the type of work being performed. During recent U.S. military operations in Iraq and Afghanistan, contractors often accounted for 50% or more of the total DOD presence in-country. For the fourth quarter of fiscal year (FY) 2018, U.S. Central Command (CENTCOM) reported 49,451 contractor personnel working for DOD within its area of responsibility, which included 28,189 individuals located in Afghanistan, Iraq, and Syria. From FY2009 to FY2018, obligations for all DOD-funded contracts performed within the Iraq and Afghanistan areas of operation totaled approximately $208 billion in FY2019 dollars. In late 2017, the DOD stopped reporting the number of U.S. military personnel deployed in support of operations in Afghanistan, Iraq, and Syria as part of its quarterly manpower reports and in other official releases. These data remain withheld.