On October 4, four members of U.S. Special Operations Forces were killed and two wounded in an attack near the town of Tongo Tongo in western Niger ( Figure 1 , below). The Defense Department (DOD) has stated that the U.S. servicemembers were "conducting an advise and assist mission" to conduct reconnaissance with Nigerien counterparts, several of whom were also killed and injured. For many Members of Congress, the incident has thrown a spotlight on evolving security threats in West Africa's central Sahel region, as well as the growing presence of U.S. military forces engaged in counterterrorism support in Africa and throughout the world. This report provides background information and context on the U.S. military presence in Niger, and several related issues, in response to frequently asked questions. U.S. officials have stated that a local group affiliated with the Islamic State (IS, aka ISIS/ISIL) was responsible for the attack, which would make it the first known incident in which an Islamist militant group in the Sahel has killed U.S. soldiers on active duty. Islamist extremists have, however, killed Western civilians, including a handful of U.S. citizens, in a series of mass-casualty attacks in North and West Africa since 2013 (see chronology in the Appendix ). The first U.S. citizen reportedly held as a hostage for a prolonged period by an Islamist group in the Sahel was kidnapped in western Niger in October 2016; some news reports suggest that he is being held by the same group that carried out the October 4, 2017, attack, but this has not been confirmed. Niger's relative stability, willingness to partner with Western militaries, and close historic relationship with former colonial power France have made it an attractive partner for the U.S. military and a useful location from which to conduct activities with a regional scope. Congress has shaped U.S. engagement with Niger and the U.S. military footprint in the country through its authorization and appropriation of funding for U.S. security cooperation and assistance programs, and through its authorization of funding for U.S. military construction. Congressional committees of jurisdiction have also influenced U.S. policy and programs in Niger through oversight activities, for example probing the capacity of fragile states such as Niger to absorb U.S. counterterrorism assistance and directing DOD to seek to mitigate associated risks (see " For what purposes are U.S. military personnel in Niger? "). In response to heightened public attention to the circumstances of the October 4 incidents, many Members of Congress have noted unanswered questions about the precise nature of the DOD mission that came under attack, commanders' determinations regarding the circumstances of the mission, and the timeline under which U.S., French, and contractor-administered military assets responded to the attack. Those issues, among others, are the subject of ongoing DOD and FBI investigations, and are beyond the scope of this report. Niger is surrounded by countries beset by armed conflicts, including Mali, Nigeria, and Libya. Niger has arguably managed its security challenges more adeptly than some countries in the region, but political instability, ethnic rebellions, and military interference in politics have posed recurrent challenges. Niger has never had a democratic transition between two civilian leaders. It is among the world's poorest countries and has faced periodic humanitarian emergencies. Niger is also a key transit point for African migrants seeking to reach Europe via Libya's Mediterranean coast. Smuggling of goods and people has long been a key source of income for communities in Niger's border regions—some of whom have periodically rebelled against the government. The number and geographic spread of Islamist armed groups in the central Sahel have ballooned since the Libya and Mali crises began in 2011. Several groups claiming affiliation with either Al Qaeda or the Islamic State are active in various parts of Niger. Elements of Al Qaeda in the Islamic Maghreb (AQIM), an Algerian-led regional network active in North and West Africa, are active along Niger's western border with Mali and in the vast desert north of the country, along with several AQIM splinter factions and offshoots. One AQIM offshoot has pledged allegiance to the Islamic State (see " What do we know about the perpetrators? " below). Separately, southeastern Niger is affected by the Boko Haram conflict, which spilled beyond Nigeria's borders into the surrounding Lake Chad Basin subregion in 2015. Group allegiances and alliances in the Sahel tend to be fluid, and the practical implication of pledges of allegiance to transnational actors is often hard to assess. Thus far in Niger, Islamist extremist groups have posed a threat primarily to the country's internal security and to Western personnel and interests located there. Such groups regularly attack local targets—especially government officials, prisons, schools, and individuals accused of collaborating with the state or with French-led counterterrorism operations—in the triborder region between Niger, Mali, and Burkina Faso (see Figure 1 , above). On the Mali side of the border, there have been frequent attacks against U.N. peacekeepers, many of whom are West African. Islamist extremist groups active in the Sahel have kidnapped multiple Western nationals for ransom over the past 15 years, and since 2015, AQIM-aligned groups have carried out a string of mass-casualty attacks targeting locations popular with Westerners (see Appendix ). In addition to aforementioned Islamist factions, a range of other armed groups operate in western Niger and in adjacent areas of Mali and Burkina Faso. These include ethnic militias, separatist rebels, drug traffickers, smugglers, and bandits, with the lines among categories often blurred. In their efforts to recruit local adherents, Islamist armed groups in the central Sahel have exploited local communal-level conflicts and grievances, as well as reportedly widespread frustrations at perceived local government ineptitude and corruption. Some analysts assert that the often heavy-handed counterterrorism approach of local security forces in the subregion has contributed to worsening instability. In a press conference on October 23, Joint Chiefs of Staff Chairman General Joseph Dunford acknowledged that the area where U.S. troops came under fire is "inherently dangerous," noting, "we're there because ISIS and Al-Qaeda are operating in that area. That's why our forces are providing advice and assist to local forces is to help them to deal with that particular challenge." He added, with respect to the October 4 incident, that the decision to approve the mission was premised on a "judgment of [potential] contact with the enemy ... at a particular location at a particular time." The State Department "recommends U.S. citizens avoid travel to Niger's border regions, particularly the Malian border area, Diffa region and Lake Chad Basin area because of activity by extremist groups." On October 21, unidentified gunmen killed 13 Nigerien gendarmes in a village not far from the site of the October 4 attack. Niger's government seeks to work with other countries in the region to counter terrorism and has welcomed outside assistance, including from Western militaries. In the southeastern region of Diffa, Niger's military participates in a Nigeria-led Multi-National Joint Task Force (MNJTF) to counter Boko Haram. Five countries known as the G-5 Sahel, including Niger, have also proposed a similar joint force to pursue terrorist groups and enhance border security, starting in the Niger/Mali/Burkina Faso triborder region. The G-5 Sahel member states have developed a budget estimate of about $500 million to make the force fully operational, and they and the African Union (AU) have requested greater donor support. Troops from Niger have also partnered closely with France's Operation Barkhane, under which French troops are conducting counterterrorism operations in the Sahel, both unilaterally and with African partner forces. Some Nigeriens have protested the increased deployment of Western troops in Niger since 2013, and some observers have raised concerns that a popular backlash against the growing foreign military presence could pose new challenges to Niger's internal stability. The U.S. military presence in Niger is among the largest the United States has in Africa. In June 2017, the White House reported to Congress that about 645 U.S. armed military personnel were stationed in Niger to support counterterrorism operations by "African partners." Following the October 4 attack, DOD officials have publicly cited a larger figure of 800 U.S. military personnel in Niger. These figures presumably comprise personnel stationed in the capital, Niamey, as well as those deployed in more remote areas. Notably, a U.S. Air Force facility is under construction in the northern city of Agadez ( Figure 1 ), which the Air Force has described as supporting U.S. logistical and intelligence capacities in the subregion, and which U.S. diplomats have described as supporting the Niger government's capacity to secure its borders. U.S. Africa Command (AFRICOM) describes the U.S. military presence in Niger, as in most places in Africa, as a "light footprint," suggesting that a more extensive and/or conventional military mission could require more extensive airlift, close air support capacity, and contingency planning. The bulk of U.S. military personnel in Niger, as elsewhere in Africa, appear to be engaged in short-term missions, which may lead personnel figures to vary over time. The U.S. military presence in Niger has grown significantly since 2002, when the George W. Bush Administration first launched an initiative to build the capacity of Niger and neighboring countries to counter terrorism, and since 2013, when President Obama reported to Congress the deployment to Niger of some 100 military personnel for intelligence, surveillance, and reconnaissance (ISR) activities. Based on public documents issued by the Obama and Trump Administrations, the U.S. military presence since appears to have grown incrementally. This trend is the product of several overlapping developments, including: A stated U.S. interest in responding to the proliferation and spread of Islamist insurgent groups in West Africa since the collapse of the Qadhafi regime in Libya in 2011, the start of Mali's internal crisis in 2012, and the escalation of the Boko Haram insurgency in 2014; DOD's provision of logistical and intelligence support for France's multicountry counterterrorism operation in the Sahel, Operation Barkhane, which France launched in 2014 following its 2013 military intervention in Mali; and An interest, both in Congress and under the George W. Bush and Obama Administrations, in "building partner capacity" to counter terrorism, in part as a stated effort to preclude large-scale U.S. combat operations (see " What are the broader implications of building partner capacity? "). AFRICOM stated on October 20, 2017, that the U.S. military did not have an "active, direct combat mission" in Niger. Some news reports suggest that DOD could initiate direct military strikes there in the future, including possibly as a result of the October 4 attack. DOD officials have declined to comment publicly on any such plans, and have not publicly discussed the potential implications of any change in mission for the U.S. military posture in the region. News reports and statements by Trump Administration officials suggest that the Administration has generally sought to reduce policy limitations on military operations in countries where Islamist militants are active but where the United States has not previously engaged in combat operations, which could have implications for countries such as Niger. More broadly, the United States has pursued counterterrorism goals in the Sahel on an interagency basis for at least the past 15 years through a range of programs, including security assistance, military-to-military engagement, development and democracy-promotion assistance, and programs that aim to counter violent extremist ideology. Since the early 2000s, U.S. officials have come to see Niger as a key counterterrorism partner in North-West Africa due to its relative stability within a turbulent region and its openness to partnering with Western militaries, including those of the United States and France. State Department and DOD resources for security assistance and cooperation programs in the Sahel have increased significantly in recent years in the aftermath of events in Mali in 2012, when AQIM and related groups briefly asserted control over northern Mali, and following the escalation in 2014 of the Boko Haram conflict in northeast Nigeria and the adjacent Lake Chad Basin region. According to public documents issued by the Obama and Trump Administrations, U.S. military personnel in Niger are involved in a range of activities, including: ISR operations based out of sites in Niamey and/or Agadez. Military construction activities in Agadez (as discussed above). Logistical and intelligence support to France's Operation Barkhane. Implementation of security cooperation and assistance programs for Niger, focusing on goals ranging from counterterrorism to peacekeeping and "defense institution building." Periodic joint combined exercises and training engagements (JCETs), along with larger annual multinational exercises in the region, such as Flintlock. Advisory activities in which U.S. personnel are embedded with local security forces, as was apparently the case in the mission that came under attack on October 4, according to DOD officials. This mix of activities has evolved over time. A number of counterterrorism assistance programs are carried out in the Sahel under the State Department-led Trans-Sahara Counterterrorism Partnership (TSCTP), an interagency initiative launched over a decade ago to build the capacity of countries in North and West Africa, including Niger. U.S. military personnel implement some aspects of TSCTP, and at least one DOD named operation in the Sahel supports the program by providing training, equipment, assistance, and other advice to partner nation armed forces. Congress has periodically sought to assess the effectiveness of TSCTP and conducted oversight of its funding resources. DOD-administered security cooperation activities have expanded in Niger and elsewhere in Africa over the past decade, as Congress has provided increased authorities and funding for DOD efforts to build the capacity of foreign partner forces for counterterrorism and certain other purposes. Under evolving authorities, DOD has funded and implemented programs in countries, such as Niger, that have generally received relatively limited State Department-administered security assistance resources. Niger has become a top beneficiary in Africa of DOD "global train and equip" programs for counterterrorism purposes, with about $170 million in planned funding cumulatively notified to Congress to date. The influx of DOD security cooperation resources for these programs has been accompanied by congressional concerns as to their effectiveness, and with the ability of fragile states to absorb and maintain U.S.-origin equipment and capabilities. Such concerns have been expressed in recent strategy and reporting requirements, and in directives related to monitoring-and-evaluation, that have been enacted in defense authorization measures (e.g., §1211 and §1278 of P.L. 113-291 ; §1202 of P.L. 114-92 ; and §1205 and §1273 of P.L. 114-328 ). Reflecting similar concerns, Congress has directed DOD to conduct foreign "defense institution building" (DIB) activities in countries receiving DOD-administered security cooperation for certain purposes, including counterterrorism, under Section 333(c)(4) of P.L. 114-328 . Among other issues, recent trends have also raised challenges with regard to DOD's global force management (as discussed below). DOD support to French military operations in the Sahel has been another area that Congress has encouraged through legislation. Notably, the FY2016 NDAA authorized DOD to "provide support to the national military forces of allied countries for counterterrorism operations in Africa," including "logistic support, supplies, and services," on a nonreimbursable basis. Finally, Congress has authorized funds for the Air Force's construction of the facility in Agadez, which is being pursued by active duty military personnel. With regard to U.S. Armed Forces operating in Niger, President Obama first notified Congress, "consistent with the War Powers Resolution," of a deployment of U.S. Armed Forces to that country on February 22, 2013, stating: This deployment will provide support for intelligence collection and will also facilitate intelligence sharing with French forces conducting operations in Mali, and with other partners in the region.... The recently deployed forces have deployed with weapons for the purpose of providing their own force protection and security. Providing an explanation of applicable constitutional and/or legislative authority, President Obama stated that he had directed the deployment "pursuant to my constitutional authority to conduct U.S. foreign relations and as Commander in Chief and Chief Executive" but did not cite other authority, such as the 2001 Authorization for Use of Military Force (AUMF; P.L. 107-40 ; 50 U.S.C. §1541 note), which Congress passed after the September 11, 2001, terrorist attacks against the United States. Subsequent notifications updating Congress on the status of U.S. Armed Forces in Niger and elsewhere in West Africa—including a letter issued by President Trump, "consistent with the War Powers Resolution," in June 2017—also have not specifically referred to 2001 AUMF authority as the legislative basis for a deployment to Niger. Questions that Congress may pose to the Administration include whether armed extremist groups operating in Niger that reportedly have links to Al Qaeda and the Islamic State might therefore be considered "associated forces" of the terrorist groups responsible for the 9/11 attacks. Members of Congress may also consider new legislative language to address U.S. military operations in Niger and elsewhere in Africa. U.S.-Niger diplomatic ties have grown as successive Administrations have come to see the country as a bulwark against terrorism in the Sahel, and as a result of efforts by Congress and the Obama Administration to expand U.S. food security assistance to poor countries in Africa. Secretary of State Rex Tillerson, in an August 2017 statement recognizing Niger's National Day, pledged to "continue to work with Niger to encourage economic growth, assist with counterterrorism efforts, and support a vibrant civil society." In his Senate confirmation hearing in early October, U.S. Ambassador to Niger-Designate Eric Whitaker stated that, "If confirmed, I'll draw upon my experience to expand the strong partnership between Niger and the United States of America as we continue to work together toward our mutual goals of combating extremism throughout the region, strengthening democratic governance and respect for fundamental freedoms, and fostering inclusive economic growth and prosperity." Niger has been a top recipient of U.S. security assistance in Africa over the past decade. A number of programs administered by the State Department and DOD aim to improve Niger's capacity to counter terrorism, secure its borders, and participate in international peacekeeping operations. Niger has also received security sector assistance under the Security Governance Initiative, launched by the Obama Administration, centered on Niger's national security framework and effective use of defense resources. U.S. officials have described Niger's military as relatively effective by regional standards, and Niger's human rights record has not been as severely troubled as those of other key U.S. counterterrorism partners in West Africa, such as Nigeria and Cameroon. Executive branch officials have nonetheless periodically expressed concern that high levels of U.S. security assistance for Niger, which has no bilateral USAID mission and has generally received relatively little assistance for development or democracy promotion, could have negative unintended consequences. Possibly reflecting, in part, an effort to address a perceived imbalance between military and civilian engagement with Niger, USAID-administered regional aid funding for Niger increased during the latter years of the Obama Administration, and in 2016, the United States and Niger signed a $437 million Millennium Challenge Corporation (MCC) Compact focusing on agricultural development. Ambassador-designate Whitaker also said during his confirmation hearing that, "I will be consulting with AFRICOM as well [to] get a better handle on their programs, and trying to make sure we have some greater balance in our relationship." Niger's continued eligibility to receive MCC assistance is contingent on its respect for democratic norms and the effectiveness of its anticorruption efforts. Notably, the U.S.-based organization Freedom House, whose research helps determine MCC eligibility, downgraded Niger's political rights rating in 2017 due to "repressive conditions surrounding the 2016 presidential and legislative elections, including harassment of the opposition, as well as alleged irregularities in the balloting itself." The new rating will presumably be reflected in future MCC scorecards. The Trump Administration has proposed changes to foreign aid that could have implications for bilateral ties, if implemented. In its FY2018 foreign aid budget request, the Administration proposed to eliminate the global Food for Peace program under P.L. 480 Title II, through which Niger received $33.8 million in food aid in FY2016 (latest available), and to decrease other bilateral aid for Niger to $1.6 million, from $3.1 million in FY2016. These figures, however, do not encompass MCC-administered funding or funds administered via USAID regional initiatives. General Dunford, in his October 23 press conference, stated that there are about 6,000 U.S. troops deployed in Africa, including personnel charged with guarding U.S. diplomatic facilities. The vast majority are reportedly positioned in Djibouti, the only country in Africa to host an enduring U.S. military "forward operating site." News reports, citing DOD sources, indicate that the 6,000 figure includes an estimated 1,000 members of Special Operations Forces, including those involved in advise-and-assist missions in various countries. In his 2017 Posture Statement, AFRICOM Commander General Thomas D. Waldhauser stated that the command was operating in support of the following five "Lines of Efforts." Neutralize al-Shabaab and transition the security responsibilities of the African Union Mission in Somalia (AMISOM) to the Federal Government of Somalia; Degrade violent extremist organizations in the Sahel [and] Maghreb and contain instability in Libya; Contain and degrade Boko Haram; Interdict illicit activity in the Gulf of Guinea and Central Africa with willing and capable African partners; Build peacekeeping, humanitarian assistance, and disaster response capacity of African partners. Below is a list of countries where U.S. officials have publicly confirmed a U.S. military deployment. The list is not necessarily comprehensive. U.S. news media, for example, have reported a U.S. military presence in several countries not listed below, such as Burkina Faso and Nigeria. Furthermore, nearly every country in Africa hosts some U.S. military personnel presence, for example as part of the Defense Attaché Office, Office of Security Cooperation, and/or Marine Security Detachment at U.S. Embassies. (Such personnel would appear to be included in the overall 6,000-troop figure above.) In several African countries, a limited number of DOD personnel also serve as military staff officers in U.N. peacekeeping operations. The Defense Department also conducts regular joint combined exercises and training engagements, and periodic military exercises, with African partners, which involve the temporary deployment of U.S. military personnel to the continent. Cameroon . A letter submitted by the White House to House and Senate leadership in June 2017, "consistent with the War Powers Resolution" (henceforth, the June 2017 WPR report), stated, "In Cameroon, approximately 300 United States military personnel are also deployed, the bulk of whom are supporting United States airborne intelligence, surveillance, and reconnaissance operations in the region." Chad . In his March 9, 2017, AFRICOM Posture Statement to the Senate Armed Services Committee, AFRICOM Commander General Waldhauser stated that the United States had assumed six-month rotational leadership of the Chad-based "Coordination and Liaison Cell," which coordinates international support to the Nigerian-led Multinational Joint Task Force against Boko Haram. Djibouti . In his 2017 AFRICOM Posture Statement, General Waldhauser stated that U.S. forces "remain deployed to Djibouti, including for purposes of posturing for counterterrorism and counter-piracy operations in the Horn of Africa and Arabian Peninsula and contingency support for embassy security augmentation in East Africa." Kenya . The June 2017 WPR report stated that, "Additional United States forces are deployed to Kenya to support counterterrorism operations in East Africa." Libya . The June 2017 WPR report noted several U.S. airstrike campaigns against ISIS targets in Libya since 2016, which it described as "conducted at the request of and with the consent of the Government of National Accord." Mali . In his 2017 AFRICOM Posture Statement, General Waldhauser stated that "we continue to support France's counterterrorism operations in Mali ... and seek to increase our synchronization and coordination with their efforts. Continued [U.S.] airlift and logistical support is essential to France's efforts, and we must continue to provide this support if progress is to happen in this volatile region." Senegal . A U.S.-Senegal bilateral defense access agreement was notified to the Senate in 2016, and was described by the then-U.S. Ambassador in remarks to the press. Somalia . The June 2017 WPR report stated that, "In Somalia, United States forces continue to counter the terrorist threat posed by al-Qa'ida and its Somalia-based associated force, al-Shabaab, and ISIS-Somalia. United States forces also advise, assist, and accompany regional forces, including Somali and African Union Mission in Somalia (AMISOM) forces, during counterterrorism operations." Tunisia . General Waldhauser, during a press briefing on March 24, 2017, stated in response to a question, "flying intelligence, surveillance and reconnaissance drones out of Tunisia has been taking place for quite some time ... it's not a secret base. And it's not our base, it's the Tunisians' base." Central Africa . The June 2017 WPR report noted that the six-year U.S. advisor mission to help regional forces counter the Lord's Resistance Army, known as Operation Observant Compass, ended in April 2017 and that the approximately 410 military personnel who remained at that point deployed to the subregion—in Uganda, Central African Republic, South Sudan, and Democratic Republic of the Congo—were "conducting retrograde activities." General Waldhauser also told reporters in April that, "We will continue to work with those countries with training and exercises ... we do not want to leave a void there." The future U.S. military footprint remains to be seen. In the initial aftermath of the October 4 attack, news reports questioned whether DOD had adhered to a "golden hour standard" for medical evacuation. The "golden hour" is described as the first 60 minutes following trauma or the onset of acute illness, where chances of a patient's survival are considered greatest if advanced trauma life support can be provided. DOD notes that, "historically, wound data and casualty rates indicate that more than 90 percent of all casualties die within the first hour of severe wounding without advanced trauma life support." U.S. military medical support is generally structured to meet this standard of one hour or less. Transporting a soldier to advanced trauma care within 60 minutes is viewed, however, as a standard but not an absolute requirement. Lack of medical assets—particularly aerial medical evacuation—along with distances from the site of wounding or injury to a military medical facility, the tactical situation on the ground (e.g., hostile fire), the nature of the mission (e.g., clandestine or in a remote or denied area), and adverse weather might make the one hour advanced treatment standard difficult to achieve. In these instances, commanders may assume a greater degree of risk and possibly implement mitigation measures, such as providing additional on-the-spot medical support. AFRICOM officials have long bemoaned what they characterize as the "tyranny of distance" within the command's area of operations, and, in the aftermath of the 2012 Benghazi attacks, have sought to improve the command's ability to respond more rapidly to crises involving U.S. government personnel, while continuing to call for more resources. In the case of the October 4 Niger ambush, at least one Special Forces medic (see below) was present, but he was killed during the ambush. DOD stated the two U.S. soldiers wounded during the ambush were medically evacuated by French air assets to Niamey during the firefight, and that this medical evacuation was "consistent with the casualty evacuation plan that was in place for this particular operation." The strategic rationale for which many U.S. soldiers are deployed to Niger is to assist local partners as they build their military capabilities and capacities. The September 11, 2001, terrorist attacks and the subsequent "global war on terror" provided the impetus for Congress and the executive branch to expand DOD's security cooperation and assistance tools under the rubric of building partner capacity (BPC). According to the 2006 Quadrennial Defense Review (QDR), BPC was, in essence, a maximalist interpretation and employment of a concept normally executed by Special Operations Forces when working "by, with, and through" partner forces on the ground. An increasing interest in BPC reflected assumptions that, much like Afghanistan before 9/11, fragile or "ungoverned" states could ultimately become areas in which terrorist groups could plan and execute attacks against the United States and its allies. Over time, BPC has become a preferred, if not primary, means by which the United States could secure its interests—as well as a national security objective in its own right. Yet persistent challenges with U.S. BPC missions have led some observers to question the overall strategic efficacy of conducting them. Challenges associated with such efforts in Afghanistan and Iraq, in particular, have called into question whether these BPC programs can achieve their desired effects. In the Sahel, as well, some DOD officials have negatively assessed the impact of certain types of BPC missions for counterterrorism purposes. These questions become starker when juxtaposed against larger concerns that DOD is overstretched relative to the challenges with which it must grapple. On October 4, 2017, four U.S. soldiers reportedly participating in a joint U.S.-Nigerien train, advise, and assist reconnaissance mission were killed in southwest Niger, as a result of hostile fire. All the soldiers who were killed were assigned to 3rd Special Forces Group (Airborne) from Fort Bragg, North Carolina: Staff Sergeant Bryan C. Black, 35, of Puyallup, Washington, Military Occupation Specialty (MOS) 18D, Special Forces Medical Sergeant; Staff Sergeant Dustin M. Wright, 29, of Lyons, Georgia, MOS 18C Special Forces Engineer Sergeant; Staff Sergeant Jeremiah W. Johnson, 39, of Springboro, Ohio, MOS 74D Chemical, Biological, Radiological, and Nuclear Specialist; and Sergeant La David T. Johnson, 25, of Miami Gardens, Florida, MOS 91B Wheeled Vehicle Mechanic. Two unidentified U.S. soldiers were also wounded in the attack. General Dunford stated on October 23 that Sergeant La David T. Johnson became missing in action (MIA) during the ambush and was killed on October 4, 2017, but that his body was not located until October 6, 2017, by Nigerien forces. There has been a great deal of speculation as to why Sergeant Johnson's remains were not located and evacuated until October 6, 2017, in response to which DOD officials note that an investigation of the incident is ongoing. As of October 26, no one has publicly claimed responsibility for the October 4 attack. DOD officials have identified the perpetrators as local militants "affiliated" with the Islamic State organization (IS or ISIS/ISIL). Given the location of the attack, analysts have interpreted the term as referring to the so-called Islamic State-Greater Sahara (IS-GS), a militant faction formerly associated with the Algerian-led regional network AQIM. IS-GS emerged in May 2015, when Abu Walid al Sahrawi, a leader in the Movement for Unity and Jihad in West Africa (MUJAO after its French acronym)—itself a splinter faction of AQIM—pledged allegiance to the Islamic State. In September-October 2016, the group reportedly carried out three relatively sophisticated attacks, two deadly assaults on local security forces in Burkina Faso and an attempted prison break in Niger on the outskirts of Niamey. The "core" Islamic State organization subsequently appeared to recognize the IS-GS pledge of allegiance in a public release in October 2016, although IS leadership apparently has not referred to a full "province" in the Sahel region, as it has with affiliated groups in Nigeria and Libya, for example. The degree of antagonism and/or coordination between Al Qaeda and Islamic State affiliates in West Africa is a matter of debate. While the two franchises may compete for recruits and prominence, some analysts see evidence of possible cooperation. Al Sahrawi's nationality is unclear; some news sources allege that he is a refugee from the disputed territory of Western Sahara. MUJAO, the group in which Al Sahrawi first rose to prominence, was formed in 2011 as a Malian- and Mauritanian-led dissident faction of AQIM. In 2012, after the collapse of state institutions in northern Mali, MUJAO asserted control over Mali's Gao region (bordering Niger), where it appointed local administrators, security forces, and judges. During that year, AQIM and other AQIM-related groups asserted control over other parts of northern Mali and generally coexisted. In 2013, amid France's military intervention in Mali, MUJAO joined with another AQIM splinter faction led by longtime AQIM figure—and periodic AQIM rival—Mokhtar bel Mokhtar to form Al Murabitoun. Al Sahrawi's 2015 split from Al Murabitoun took place around the same time that the latter group was undertaking a rapprochement with AQIM, culminating in the formation of a new Al Qaeda-aligned coalition in Mali in early 2017 (known as Jama' at Nusrat al Islam wal Muslimeen or "Group for Supporting Islam and Muslims," aka JNIM). (See chronology in the Appendix .) Since its pledge to the Islamic State in May 2015, observers have attributed to IS-GS a number of attacks against local targets, including local security forces, officials, teachers, and prisons, in the triborder region joining Niger, Mali, and Burkina Faso. Some news reports indicate that the group is holding a Romanian national kidnapped in Burkina Faso in April 2015—a kidnapping for which MUJAO claimed responsibility—and that it may be holding the American kidnapped in Niger in October 2016, an incident that no group has publicly claimed. IS-GS has openly claimed responsibility for a small handful of attacks, making its involvement in various attacks and its broader level of activity difficult to ascertain. Niger's Interior Minister Mohamed Bazoum stated in a media interview on October 19 that those who carried out the attack were "youths under the influence of Abu Walid al Sahrawi" who were based in the Niger/Mali border region. Possibly reflecting the extremely complex nature of militant allegiances in the subregion, Bazoum also suggested that the assailants were loyal to Iyad ag Ghali, a Malian national who heads the Al Qaeda-aligned JNIM, although some analysts portray JNIM and IS-GS as rivals rather than allies. The Interior Minister indicated in his remarks that Niger's government had yet to identify the precise assailants. In 2012, the State Department designated MUJAO and two of its founders as Specially Designated Global Terrorists under Executive Order 13224. (One of the two founders was subsequently killed in a French strike in Mali.) The State Department designated Al Murabitoun (aka Al Mulathamun) in 2013 as a Foreign Terrorist Organization. Abu Walid al Sahrawi is not individually designated for U.S. sanctions. For many Members of Congress, the events of October 4 and their aftermath have highlighted broad issues and challenges related to the effective congressional oversight of U.S. military deployments, U.S. counterterrorism policy in remote regions, and executive-legislative branch information sharing. Some issues and questions for congressional consideration include the following: Counterterrorism Strategy. On October 23, 2017, Joint Chiefs of Staff Chairman General Joseph Dunford stated, "our soldiers were operating in Niger to build capacity of local forces to defeat violent extremism in West Africa. Their presence is part of a global strategy." What is the current U.S. global counterterrorism strategy and how does the presence of troops in Niger support this strategy? Through what means are DOD's counterterrorism activities in Africa coordinated with those of other federal entities, including the State Department, intelligence community, and law enforcement? What alternatives exist to the deployment of U.S. military personnel on advise and assist missions? Train, Advise, and Assist Missions. What is the policy and legal framework for the deployment of U.S. military personnel to work "by, with, and through" partner nation forces in locations, such as Niger, where there is no U.S. "active, direct combat operation"? What are the appropriate rules of engagement and roles for U.S. military personnel serving in such missions? Are new reporting or notification requirements needed for congressional oversight of such activities? Framework for Military Engagement in the Sahel. Is the legal and policy framework for U.S. military activities in the Sahel appropriate given the region's threat profile and its level of importance for U.S. national security? What might be the potential unintended consequences of an expanding U.S. military presence in the area, and how are current activities structured to avoid or mitigate them? Impact of Building Partner Capacity. Are U.S. "building partner capacity" (BPC) activities having their intended effect in Niger and elsewhere in the Sahel? How should Congress evaluate the potential risk, reward, and opportunity costs of such activities? What are the implications of Congress's expansion and consolidation of DOD's authority to conduct a range of "building partner capacity" activities under the FY2015 and FY2017 National Defense Authorization Acts (NDAAs, P.L. 113-291 and P.L. 114-328 , respectively)? What considerations should be taken into account by Members of Congress when authorizing and overseeing U.S. counterterrorism capacity-building activities that may take place in countries such as Niger—that is, fragile, impoverished states with a history of military coups and internal conflicts? What are the potential unintended consequences of U.S. counterterrorism assistance in such settings? Military Posture. Successive Commanders of U.S. Africa Command (AFRICOM) have requested additional resources for contingency planning (including personnel recovery) and intelligence, surveillance, and reconnaissance activities in support of missions in Africa. Is the military posture in the Sahel adequate and suited to the missions in which U.S. forces are engaged, as well as the security and logistical environment in the region? What new capabilities and assets might AFRICOM require, if any? At what cost should they be provided relative to other priorities? To what extent might the current set of DOD missions or prospective future missions require changes to the U.S. military posture in the region—including new assets, new access to host-nation airfields and ports, updates to any status-of-forces agreements, and changes to supply chains? Contingencies: Role of Allies and Other Actors . What role do allied countries, such as France, play in enabling U.S. military missions in the Sahel, including contingency planning? How are U.S. military activities coordinated with those of these allied forces? What role do military contractors play? DOD Global Force Management . Are deployments of U.S. military personnel for BPC missions creating strains on U.S. forces globally? Has the strategic focus on BPC come at the expense of other national security priorities? Is DOD making appropriate planning and force structure decisions to be able to respond to multiple contingencies affecting BPC missions, if necessary? To what extent might DOD need to adjust its force planning construct due to these considerations?

Summary: A deadly attack on U.S. soldiers in Niger and their local counterparts on October 4, 2017, has prompted many questions from Members of Congress about the incident. It has also highlighted a range of broader issues for Congress pertaining to oversight and authorization of U.S. military deployments, evolving U.S. global counterterrorism activities and strategy, interagency security assistance and cooperation efforts, and U.S. engagement with countries historically considered peripheral to core U.S. national security interests. This report provides background information in response to the following frequently asked questions: What is the security situation in Niger? How big is the U.S. military presence in Niger? For what purposes are U.S. military personnel in Niger, and what role has Congress played in the U.S. military presence there? Is the U.S. military presence in Niger related to the 2001 Authorization for Use of Military Force (AUMF)? What is the state of U.S.-Niger relations and aid? Where else in Africa are U.S. military personnel deployed? Medical evacuation: What is the "golden hour" and does it apply to troop deployments in Africa? What are the broader implications of building partner capacity in Niger for DOD? Who were the four U.S. soldiers killed in Niger on October 4? What do we know about the alleged perpetrators of the October 4 attack? It also identifies potential issues for Congress as Members look ahead to ongoing and future authorization, appropriations, and oversight activities. A chronology of terrorist attacks in the Sahel and related developments is provided in an Appendix. Additional details surrounding the October 4 ambush and its aftermath may continue to emerge as information becomes available. The following CRS products provide additional analysis of issues discussed in this report: CRS In Focus IF10172, Al Qaeda in the Islamic Maghreb (AQIM) and Related Groups, by [author name scrubbed]; CRS Report R44563, Terrorism and Violent Extremism in Africa, by [author name scrubbed] and [author name scrubbed]; CRS Report R42699, The War Powers Resolution: Concepts and Practice, by [author name scrubbed]; CRS Report R43983, 2001 Authorization for Use of Military Force: Issues Concerning Its Continued Application, by [author name scrubbed]; CRS Report R44313, What Is "Building Partner Capacity?" Issues for Congress, coordinated by [author name scrubbed]; CRS Report R44602, DOD Security Cooperation: An Overview of Authorities and Issues, by [author name scrubbed] and [author name scrubbed]; CRS Report RS21048, U.S. Special Operations Forces (SOF): Background and Issues for Congress, by [author name scrubbed].