The Islamic State and U.S. Policy
Released: 2018-09-25T00:00:00

Summary:
The Islamic State (IS, aka the Islamic State of Iraq and the Levant, ISIL/ISIS, or the Arabic acronym Da'esh) is a transnational Sunni Islamist insurgent and terrorist group that controlled large areas of Iraq and Syria from 2014 through 2017. The group attracted a network of global supporters and its leader, Abu Bakr al Baghdadi, received pledges of affiliation from groups in several other countries. A series of terrorist attacks attributed to the group or to individuals it has inspired have claimed hundreds of lives on four continents since November 2015, including in the United States.
While U.S. and allied forces in 2017 and 2018 successfully liberated most of the territory formerly held by the group in Syria and Iraq, IS leadership remains at large and IS fighters appear to be evolving into an insurgent force. The group's international affiliates continue to operate, and individuals inspired by the group continue to attempt attacks in Europe and elsewhere. The stabilization of areas recovered from the group in Iraq and Syria remains an ongoing challenge, and a U.S. military spokesperson for the counter-IS campaign warned in August 2018 that, "We cannot emphasize enough that the threat of losing the gains we have made is real, especially if we are not able to give the people a viable alternative to the ISIS problem."
Members of Congress, executive branch officials, and their international counterparts continue to debate a range of proposals for consolidating battlefield gains made to date and preventing the Islamic State from succeeding in its stated objectives of remaining and expanding. President Obama's goals for U.S. strategy were to degrade and ultimately defeat the Islamic State through U.S. direct military action and support for local partner forces. President Donald Trump directed his Administration to develop a comprehensive plan to defeat the group and has accelerated U.S. military operations while augmenting U.S. contributions to stabilization in liberated areas.
The U.S. military continues to conduct operations against the group in Iraq, Syria, and Afghanistan, while monitoring and occasionally striking its affiliates and personnel elsewhere. Parallel U.S. assistance efforts support stabilization in areas once held by the group, and diplomatic efforts have promoted political reconciliation among local factions in countries where Islamic State supporters are active. The United States also provides security assistance to partner governments in support of operations against Islamic State affiliates and to strengthen the ability of partners to deter and respond to Islamic State attacks. Evolving counterterrorism cooperation and intelligence sharing efforts among a wider network of concerned governments seek to further limit the ability of IS supporters to carry out transnational terrorist attacks.
Interrelated conflicts and political crises in Iraq, Syria, and other countries where the Islamic State operates complicate efforts to address and durably eliminate the threats posed by the group. Military operations may reduce the numbers of IS fighters and liberate IS-held territory, but the underlying political disputes and development challenges that the Islamic State has exploited may create ongoing openings for the group if governance and reconstruction needs go unmet. Governments may continue to face difficult decisions about the potential risks and rewards of various military, law enforcement, surveillance, intelligence sharing, financial, border security, refugee admission, and consular countermeasures.
This report provides background on the Islamic State organization, discusses its goals, operations, and affiliates, reviews U.S. legislative and policy debates, and reviews relevant legislation from the 114th and 115th Congresses. For more information, see CRS Report RL33487, Armed Conflict in Syria: Overview and U.S. Response; CRS Report R45096, Iraq: In Brief; CRS Report R43760, A New Authorization for Use of Military Force Against the Islamic State: Issues and Current Proposals; and, CRS In Focus IF10328, The Islamic State.

subsections: section_title: The Islamic State
paragraphs: The Islamic State organization (IS, aka the Islamic State of Iraq and the Levant, ISIL/ISIS, or the Arabic acronym Da'esh ) emerged as a major international security threat amid more than a decade of conflict in Iraq after 2003 and the outbreak of unrest and conflict in Syria in 2011 (see Appendix A ). The group's core mem bership remains in Iraq and Syria, and its efforts have been bolstered by a network of foreign fighters and affiliate groups in several countries across the Middle East, Africa, and Asia (see Appendix B ). The Islamic State's apocalyptic ideology, its revolutionary intent toward the strategically important Middle East, and its embrace of transnational terrorism have alarmed policymakers around the world and spurred global debate over strategies and policy options for defeating the group. As the area under the Islamic State's control in Iraq and Syria has been progressively eliminated ( Figure 1 ), policymakers have considered how to address the threats the group still poses as it evolves, and are debating how best to stabilize recaptured areas.
subsections: section_title: Posture and U.S. Threat Assessments
paragraphs: The Islamic State no longer occupies the vast areas of northern and western Iraq and central and eastern Syria that it once held and exploited. From 2014 through 2018, it lost large amounts of territory it had captured between 2013 and 2017, and thousands of personnel. These losses resulted from military operations by the U.S.-led international coalition and a number of U.S.-backed local forces. Nevertheless, Defense Department officials assess that the Islamic State "is well-positioned to rebuild and work on enabling its physical caliphate to re-emerge," and "probably is still more capable than Al Qaeda in Iraq at its peak in 2006-2007, when the group had declared an Islamic state and operated under the name Islamic State of Iraq...." From a counterterrorism and broader security perspective, U.S. officials assess that the group is prosecuting active insurgent campaigns in Iraq and Syria and remains a threat in and beyond these areas. 
According to some U.S. estimates, approximately 30,000 current and former IS personnel may remain present in areas of Syria and Iraq. U.N. reports make similar estimates and assessments. Other coalition officials have stated that, "that number seems a bit high" and estimated that there are "over a thousand" IS fighters in the Middle Euphrates River Valley. As of August 2018, coalition officials assess that fewer IS fighters are actively fighting from among this wider population, but point to their broader estimates to suggest that the group retains considerable ability to draw strength from supporters who have otherwise curtailed their activity for self-preservation or strategic reasons. Coalition officials assess that morale among IS supporters has worsened since the group's high point and that the group's finances, recruitment streams, communications, public outreach, and leadership have been substantially disrupted. 
U.N. estimates describe the Islamic State as "reverting from a proto-State structure to a covert network" and cite information provided by Member States in judging that "the collective discipline" of the Islamic State group is "intact," as are some of its key bureaucratic entities. Official IS media output has declined since its 2014-2015 high point but has rebounded from its 2017 low points, with output now focused equally on operations in Syria and Iraq and actions by affiliated groups elsewhere.
In March 2017, U.S. officials estimated that as many as 40,000 individuals from more than 110 countries had traveled to Syria and/or Iraq to engage in combat as members of various armed groups since 2012. According to the ODNI, this figure included more than 6,600 Westerners, including Europeans and some U.S. citizens. Hundreds of these Western foreign fighters, including dozens of U.S. citizens, joined the ranks of the Islamic State.
As of mid-2018, U.S. and international reports concluded that few new foreign fighters now travel to Syria or Iraq, but also noted that the net flow of fighters away from these countries "remains lower than expected." This may be attributable to difficulties in travel and attrition. Researchers underscore that the population of foreign fighters that travelled to these countries after 2011 "is larger, more global, and more diverse in terms of age, gender and experience in the conflict zones" than previous such cohorts. According to a March 2018 United Nations assessment, "these differences make the potential challenges associated with returnees and relocators significantly bigger, but also more complex" than in the past. The Islamic State's affiliate in Afghanistan reportedly has the highest percentage of foreign fighters among the group's affiliates, and significant numbers of fighters of European origin have returned to their countries of origin. North African and Arab Gulf states also have reported returning fighters.
It remains to be seen whether and how the Islamic State's significant territorial losses since 2017 will impact its ability to plan, direct, or fund attacks outside of Syria and Iraq. In February 2018, the U.S. intelligence community assessed that the Islamic State "almost certainly will continue to give priority to transnational terrorist attacks," and that "U.S.-based homegrown violent extremists (HVEs) will remain the most prevalent Sunni violent extremist threat in the United States." One recent study found that despite a significant reduction in the number of successful IS attacks in Europe and North America in 2018, the number of attempted IS attacks in Europe has remained unchanged. This has led some analysts to assess that there is "no correlation" between the Islamic State's loss of territory and the level of threat the group poses to the West.
The Obama Administration's strategy for reducing the threats posed by the Islamic State was predicated on the principle of working "by, with, and through" U.S.-supported local partners as an alternative to large and direct applications of U.S. military force and/or large investments of U.S. personnel and resources. The Trump Administration has maintained this general partnership-based approach but also has made some changes, including the temporary deployment of additional U.S. military personnel to both Iraq and Syria. U.S.-led coalition operations and coalition-backed offensives by local partner forces enabled the recapture of IS strongholds at Mosul, Iraq and Raqqah, Syria in 2017. As of August 2018, only isolated pockets of IS control remain in or near Syrian-government controlled parts of eastern Syria, and U.S. officials state their intent to launch "a very significant military operation" against "ISIS fighters holed up in a final area of the Middle Euphrates Valley," followed by efforts "to train local forces to hold the ground to make sure that the area remains stabilized so ISIS cannot return." 
The challenges associated with defeating the Islamic State as a military force capable of controlling territory have receded, but have been replaced by overlapping policy challenges related to preventing the group's remnants from becoming a chronic insurgent threat. U.S. relations with the government of Syria appear likely to remain hostile, and U.S. relations with Iraq are uncertain amid ongoing government formation negotiations. The Trump Administration and Congress continue to review U.S. plans for assistance to state and non-state partner forces and for the stabilization of conflict-affected areas in light of these circumstances.
Congress has authorized and appropriated funds for the continuation of U.S. military operations against the Islamic State, for the continued training and equipping of partner forces, and for the stabilization of areas recaptured from the Islamic State. State Department officials have stated that the Trump Administration it is committed to pursuing and achieving the enduring defeat of the Islamic State and has announced new personnel appointments and stabilization funding decisions in pursuit of U.S. objectives. Congress has requested that the Administration provide lawmakers with a new articulation of its strategies toward the Islamic State and toward Syria and Iraq, and may pose additional questions about Administration plans and priorities. The 115 th Congress has considered, but not enacted, a new authorization for the use of military force against the Islamic State and other terrorist groups ( S.J.Res. 59 ), and may consider alternative approaches and options during the remainder of the second session.
section_title: Responding to the Islamic State's Transnational Terrorist Attacks
paragraphs: Although Islamic State leaders have claimed and endorsed attacks across a wide geographic area since 2014, the role of IS leaders in planning, aiding, or directing such attacks has varied according to publicly available accounts. IS leaders have repeatedly encouraged and sought to provide ideological justifications for independently organized and executed attacks by individuals who support the organization but are unable to travel to Syria or Iraq to join its ranks. Most IS claims in the wake of such attacks have described the perpetrators as its "soldiers," whether or not the individuals in question have been publicly shown to have an operational link to or history with the organization. 
In May 2016, then-IS spokesman Abu Mohammed al Adnani urged IS supporters in Europe and the United States to carry out individual attacks, and subsequently released IS propaganda material containing both encouragement and instruction on methods for improvised attacks. The Defense Department confirmed Adnani was killed by a U.S. airstrike in September 2016. In August 2018, IS leader Abu Bakr al Baghdadi praised individual attackers active to date in Europe, Canada, and other "countries of the cross," urging others to follow their example using "what is easy to obtain" and said such attacks "equal one thousand operations where we are."
As noted above, the U.S. intelligence community assessed in February 2018 that the Islamic State poses a continuing terrorist threat to U.S. interests and partners worldwide, and stated that "U.S.-based homegrown violent extremists (HVEs) will remain the most prevalent Sunni violent extremist threat in the United States." U.S. officials and observers continue to debate the extent to which elements of the Islamic State organization based overseas have the capability to direct, support, or conduct attacks inside the United States. U.S. intelligence officials have described attempted attacks by IS supporters as "inevitable" and have stated that the size and scope of the global network of individuals mobilized to support the group suggests that related terrorist threats may persist for years to come. 
section_title: U.S. Strategy, Policy Options, and Related Issues
paragraphs: The Trump Administration has broadly continued the Obama Administration's partnership-based approach to the conflict with the Islamic State, while directing changes to U.S. military operations and U.S. assistance programs. The global coalition to defeat the Islamic State has organized its cooperative activities along "lines of effort," including direct military action, supporting Iraqi and Syrian partner ground forces, gathering and sharing intelligence, and making efforts to restrict flows of foreign fighters, disrupt the Islamic State's finances, and eliminate its leaders. 
The Trump Administration has continued progress that started under the Obama Administration in eliminating the Islamic State as a military threat in Syria and Iraq, but IS attacks in both countries continue, IS affiliates elsewhere are active, and IS leaders remain at large. U.S. intelligence community unclassified assessments note that gains have been made against the group but warn of the long-term challenges of stabilization, the likelihood of persistent insurgent and terrorist threats from IS operatives, and the dilemmas posed by outflows of foreign fighters from Iraq and Syria. 
As the Islamic State has lost ground since 2014, observers and policymakers have more frequently discussed challenges related to the governance and reconstruction of recaptured areas. U.S. officials and some Members of Congress express their desire to consolidate gains achieved to date and avoid the emergence or renewal of other conflicts. Current U.S. intelligence estimates warn that an IS-fueled insurgent campaign has begun in Syria and Iraq, foresee billions of dollars in reconstruction costs in liberated areas, and suggest that a host of complex, interconnected political, social, and economic challenges may rise from the Islamic State's ashes.
These concerns are echoed in the broader policy discussion regarding prospects for an Islamic State resurgence, even after the group no longer holds territory. According to one view, the Islamic State will seek to exploit the failed uprising against the Syrian government and "co-opt the resistance against Assad, the surviving symbol of repression, use it to fill their ranks, and establish a permanent post in the region." Proponents of this view argue that insurgencies can lie dormant as long as the grievances underlying them remain unaddressed and that the roots of the current Syrian uprising can be traced in part to the Islamist uprising suppressed by former President Hafiz al Asad in the 1970s and 1980s. Other observers have stated that the Islamic State appears to be making inroads in some areas of Iraq via small-scale attacks, only months after Iraqi officials declared victory over the group in December 2017.
subsections: section_title: Combatting the Islamic State in Complex Contexts
paragraphs: The Islamic State organization and its regional adherents have thrived in ungoverned or under-governed areas of countries affected by conflict or political instability. These permissive environments provide resources and safe-haven for IS operations and in some cases offer recruits from among disaffected local groups. Prospects and options for undermining IS supporters have been shaped by the relative success or failure of efforts to restore security, address political grievances, boost economic growth, and promote effective governance. Examples may be drawn from recent developments in places such as Iraq, Syria, Egypt's Sinai Peninsula, Libya, Afghanistan, Yemen, the Sahel, the southern Philippines, and the Lake Chad basin. 
In Iraq, the United States has emphasized the importance of providing support to inclusive security forces under central government command, maintained support for forces affiliated with the Kurdistan Regional Government on these terms, and sought to preserve Iraq's political and territorial unity pursuant to its constitution. U.S. assessments have identified vulnerabilities that could challenge Iraqi efforts to combat IS remnants, including lack of interagency cooperation among various security, law enforcement, and intelligence organizations, the destruction of large portions of Iraq's law enforcement infrastructure (such as prisons), and the limited capability of Iraqi security forces to prevent smuggling across the Syria-Iraq border.
In Syria, the United States has sought a negotiated settlement to the conflict that would see President Asad and some of his supporters leave office while preserving the institutions and security structures of the Syrian state. U.S. support for a predominantly Kurdish coalition of forces in northern Syria has raised some parties' concerns about relations between Arabs and Kurds in the country, relations between Syrian Kurds and Kurds in neighboring countries, and Syria's long term political and territorial integrity.
In some settings, such as Egypt and Nigeria, U.S. counterterrorism partnership with national governments and military forces may test U.S. commitments on political reform and human rights. In other settings that have lacked credible, broadly accepted governments in recent years such as Libya or Yemen, dependable partners may remain elusive and the United States and other actors may reserve the option of pursuing unilateral military action against IS affiliates and other extremist groups. Working with partners in these countries carries risks of influencing underlying political disputes in unpredictable ways or inadvertently empowering parties to local conflicts that may be hostile to U.S. security or preferences.
To the extent that U.S. and coalition strategy remains predicated on the cooperation of partner forces on the ground and the coordination of multinational efforts in the region and beyond, U.S. officials may continue to be challenged to accommodate the complimentary and competing interests of other local, regional and global actors in the pursuit of shared goals. 
section_title: U.S. Military Operations against the Islamic State
paragraphs: The Trump and Obama Administrations have considered groups and individuals associated with the Islamic State and participating in hostilities against the United States or its coalition partners to be legitimate military targets pursuant to the 2001 Authorization for the Use of Military Force (AUMF) against Al Qaeda ( P.L. 107-40 ; 50 U.S.C. §1541 note), subject to executive branch discretion. The executive branch has acknowledged military operations against Islamic State targets in Iraq, Syria, Afghanistan, Libya, the Philippines, Niger, and Somalia. In the 115 th Congress, the Senate has considered legislation ( S.J.Res. 59 ) that would replace the 2001 AUMF. 
Iraq and Syria. U.S. military operations against the Islamic State in Iraq and Syria are organized under the command of Combined Joint Task Force – Operation Inherent Resolve (CJTF-OIR). As of August 2017, U.S. and coalition forces had used combat aircraft, armed unmanned aerial vehicles, and sea-launched cruise missiles to conduct more than 24,500 strikes against Islamic State targets in Iraq and Syria since August 8, 2014, and September 22, 2014, respectively. As of March 2018, CJTF-OIR reported that U.S. military operations related to the Islamic State as part of OIR since the beginning of kinetic operations on August 8, 2014, had cost $23.5 billion.
Afghanistan. Operation Freedom's Sentinel (OFS) consists of two "complementary missions": first, since early 2015, the NATO-led mission in Afghanistan, known as "Resolute Support Mission" (RSM), has focused on training, advising, and assisting Afghan government forces; second, combat operations by U.S. counterterrorism forces, along with some partner forces, also continue and have increased since 2017, targeting the Islamic State's Khorasan Province affiliate and Al Qaeda. The Department of Defense does not disaggregate the costs of kinetic operations against the Islamic State from the wider costs of OFS operations. As of June 2018, $134.3 billion has been obligated in support of OFS since that operation began on January 1, 2015. 
Libya. The U.S. military assisted local militia forces in recapturing territory from the Islamic State's affiliate in Libya during 2016, where Operation Odyssey Lightning included a campaign of airstrikes, as well as the deployment of small numbers of U.S. military personnel to gather information and build relationships with local anti-IS groups. Periodic U.S. strikes have targeted IS personnel and other extremists in Libya since. In 2017 and 2018, U.S. Africa Command (AFRICOM) stated that "instability in Libya and North Africa may be the most significant, near-term threat to U.S. and allies' interests" in Africa, and that, in light of prevailing conditions in Libya, "the risk of a full-scale civil war remains real."
Philippines. In 2017, the Department of Defense launched Operation Pacific Eagle-Philippines (OPE-P), aimed at assisting the Philippines armed forces in defeating southern Philippines-based IS affiliates and other extremist groups. Roughly 250 U.S. military advisers, including U.S. special operations forces, provide training, advice, and assistance on a bilateral basis to the Philippines armed forces. According to the Department of Defense, OPE-P is intended to be a "short-term, targeted operation" and provides assistance exclusively at the request of the Philippines government. 
According to United States Indo-Pacific Command (USINDOPACOM), the Department of Defense had obligated or committed $89.8 million for OPE-P as of June 2018. The United States also provided two surveillance aircraft and two surveillance drones in 2017 and 2018 for counterterrorism purposes. In July 2018, the U.S. government announced that it would provide $26.5 million in State Department counterterrorism assistance to the Philippines over a two-year period. The U.S. Agency for International Development (USAID) has provided nearly $32 million for humanitarian and recovery efforts in IS-affected areas of the Philippines.
section_title: Partnership Programs
subsections: section_title: Training, Equipping, and Advising U.S. Partners in Iraq
paragraphs: U.S. military personnel have deployed to Iraq to advise, assist, and train Iraqi forces, gather intelligence on the Islamic State, and secure U.S. personnel and facilities. As of March 2018, U.S. officials reported that more than 138,000 Iraqi personnel had received training, including Iraqi Security Forces, police, Kurdish peshmerga , and Sunni tribal fighters. Iraqi and U.S. officials are consulting on the scope and terms of a longer term security partnership that may see U.S. personnel stay in Iraq to help refit, advise, and train Iraqi security forces as they seek to eliminate remaining IS fighters and prevent the group's insurgent campaign from taking hold. The U.S. military presence in Iraq is authorized by Iraq's government through an exchange of diplomatic notes that cites the security provisions of the 2008 bilateral Strategic Framework Agreement. 
U.S. contributions to training efforts in Iraq are made in part through the Iraq Train and Equip program, which Congress authorized in the FY2015 National Defense Authorization Act (NDAA, Section 1236 of P.L. 113-291 ). The NDAA for FY2019 ( P.L. 115-232 ) extended the authorization for the Iraq training program through December 31, 2020. The Office of Security Cooperation at the U.S. Embassy in Iraq also provides security force and related management assistance to the Iraqi military and other national security forces. The Trump Administration requested $850 million for Iraq Train and Equip program efforts as part of its FY2019 defense appropriations request for the Counter-ISIS Train and Equip Fund (CTEF).
section_title: Efforts to Train, Equip, and Advise Syrians40
paragraphs: Congress authorized and funded a train and equip program for vetted Syrians in 2014 for select purposes, including supporting U.S. efforts to combat the Islamic State and other terrorist organizations in Syria and promoting the conditions for a negotiated settlement to Syria's civil war (Section 1209 of H.R. 3979 , P.L. 113-291 ). The program's limited results as of September 2015, Russian military intervention in Syria, and support by some Members of Congress for broader civilian protection missions led the Obama Administration to alter the program beginning in October 2015. Obama Administration officials described their intended overall approach to the redesigned program as "transactional" and performance-based, with Syrian beneficiaries receiving U.S. support as opportunities present themselves and relative to their effectiveness on the battlefield and the alignment of their actions with U.S. interests.
The revamped train and equip program has since shifted away from training and equipping wholly new units of vetted recruits and toward equipping and enabling vetted leaders and existing groups inside Syria who are fighting the Islamic State organization. U.S.-trained, equipped, and compensated individuals are now active under the rubric of a Kurdish-Arab coalition force in northern Syria known as the Syrian Democratic Forces (SDF), an Internal Security Force in Raqqah, and the Mughawir al Thawra (MAT, Revolutionary Commandos) group in remote southeast Syria. Equipment, including some weaponry and ammunition, has been provided to SDF and other forces, and U.S. special operations personnel have been deployed to Syria to advise and assist the SDF and MAT in operations against the Islamic State. 
The underlying authority for the Department of Defense Syria train and equip program remains Section 1209 of the FY2015 defense authorization act ( P.L. 113-291 ), as amended and extended by subsequent legislation. Congress has not appropriated funds specifically for the Syria train and equip program since the program's inception. Congress has authorized the reprogramming of defense funds to operations and maintenance accounts to fund program activities subject to the prior approval of congressional defense and appropriations committees. The FY2019 NDAA ( P.L. 115-232 ) extended the authorization for the program through December 31, 2019. The Trump Administration requested $300 million in FY2019 Counter-ISIS Train and Equip Fund (CTEF) monies for Syria programs.
section_title: Outlook and Select Issues for the 115th Congress
paragraphs: U.S. officials have stated that the Islamic State is likely to evolve into an insurgency force in both Syria and Iraq, despite the success of coalition forces in significantly degrading the group's capabilities. In February 2018, the U.S. intelligence community assessed that "ISIS core has started—and probably will maintain—a robust insurgency in Iraq and Syria as part of a long-term strategy to ultimately enable the reemergence of its so-called caliphate." U.S. intelligence officials expect that the group is "likely to focus on regrouping in Iraq and Syria, enhancing its global presence, championing its cause, planning international attacks, and encouraging its members and sympathizers to attack in their home countries."
In Iraq and Syria, competition and discord between and among local actors continue to complicate U.S. objectives, as does intervention by and competition among regional and extra-regional actors, including Russia, Iran, Turkey, and the Arab Gulf States. These complications have become more immediate and relevant as IS forces have ceded territory, and, in some places, struggles have commenced over who will define the future of liberated areas.
Iraq remains mired in political and fiscal crises, with Iraqi leaders and factions competing for advantage in government formation talks amid popular demands for improved security, service delivery, and an end to corruption. Attacks on civilians, security forces, and local officials attributed to IS fighters continue across areas of north, central, and western Iraq in a pattern of violence some observers liken to the period prior to the Islamic State's reemergence as a major force in 2013 and 2014. The U.S. intelligence community assessed in February 2018 that the Islamic State "will remain a terrorist and insurgent threat, and the group will seek to exploit Sunni discontent to conduct attacks and try to regain Iraqi territory." The community further concluded that despite the group's "loss of territory, the social and political challenges that gave rise to the group remain and threaten the cohesion of the Iraqi state."
The conflict between the Asad government of Syria and armed opposition groups has shifted in favor of pro-Asad forces, but a de facto division of the country persists. Pro-Asad forces, remaining armed anti-Asad forces (including Al Qaeda affiliated extremists), and Turkish security forces control areas to the south and west of the Euphrates River, while areas to the north and east of the river are under the control of U.S.-backed Kurdish and Arab groups. U.S. and coalition forces are preparing to launch military operations against remaining IS strongholds in areas outside the Syrian government's control. Further consolidation of security control in western Syria by pro-Asad forces may encourage the government to further amplify its demands for foreign forces it considers to be hostile (including the United States) to leave Syrian territory. U.S. partners also may feel compelled to reach political and security understandings with the Syrian government that could complicate continued U.S. operations in areas under their control. 
The Trump Administration has signaled its intention to continue providing security support to Syrian partner forces to enable them to internally secure areas recaptured from the Islamic State, but it remains to be seen whether or how reassertion of authority by the Asad government might affect U.S. plans. As noted above, U.S., coalition, and local partner forces have degraded the Islamic State's ability to operate in much of Syria, but it is not certain that the Asad government, its partners, and U.S. partners would be able to maintain and consolidate these gains in the absence of U.S. and coalition operations and support.
Members of Congress continue to debate the proper means and ends for U.S. efforts to combat the Islamic State organization while exercising oversight over U.S. military operations and a wide array of other counter-IS programs. Since 2014, Congress has authorized and appropriated billions of dollars for military operations and new types of nonlethal and lethal assistance for select groups and forces in Iraq, Syria, and Afghanistan, but has not passed a new authorization for the use of military force against the Islamic State. Key questions in ongoing executive and legislative policy debates include the following:
How should the United States balance the use of diplomatic, military, intelligence, economic, and law enforcement tools in responding to various IS-related threats? How can the United States best undermine the appeal of the Islamic State's ideology? Should the United States prioritize the fight against the Islamic State, prioritize efforts to stabilize Syria and other countries where IS forces operate, or pursue counter-IS operations and stabilization simultaneously? How have military operations that have recaptured territory from the Islamic State affected the threat that the group poses? Which forces should carry out future military and counterterrorism operations against the group, and what support or direction should the U.S. government provide? What political and military arrangements might best keep extremists from returning to recaptured areas or drawing new support? What stabilization assistance might be needed? Who will provide it, for how long, and on what terms? What should be done to address short and long term risks posed by returning foreign fighters in numerous countries? What unique challenges do foreign fighter issues pose in various places and what should the U.S. approach be? Does lasting progress against the Islamic State depend on durably altering the political dynamics of Iraq, Syria, and other locations where the Islamic State has attracted supporters? How should the evolving IS threat shape overall U.S. policy toward Syria and Iraq, the provision of assistance to U.S. partners there, and U.S. policies toward displaced persons and stabilization? What effects might U.S. assistance for government security forces and select subnational actors in the fight against the Islamic State have on broader and longer term security and political conditions in various countries of interest?
Appendix A. Emergence and Organizational Development
Roots in Iraq and Syria
The Islamic State's direct ideological and organizational roots ( Figure A-1 ) lie in the forces built and led by the late Abu Musab al Zarqawi in Iraq from 2002 through 2006— Tawhid wal Jihad (Monotheism and Jihad) and Al Qaeda in the Land of the Two Rivers (aka Al Qaeda in Iraq, or AQ-I). Zarqawi took advantage of Sunni animosity toward U.S. forces and feelings of disenfranchisement at the hands of Iraq's Shia and Kurds to advance a uniquely sectarian agenda that differed from Al Qaeda's in important ways. Some experts attribute Sunni resentment to the use by some Shia of the democratic political process to monopolize political power in Iraq. Following Zarqawi's death at the hands of U.S. forces in June 2006, AQ-I leaders repackaged the group as a coalition called the Islamic State of Iraq (ISI). ISI lost its two top leaders in 2010 and was weakened, but not eliminated, by the time of the U.S. withdrawal in 2011. The precise nature of ISI's relationship to Al Qaeda leaders from 2006 onward is unclear.
Under the leadership of former U.S. detainees Ibrahim Awad Ibrahim al Badri al Samarra'i (aka Abu Bakr al Baghdadi), Taha Subhi Falaha (aka Abu Mohammed al Adnani), and others, the Islamic State of Iraq rebuilt its capabilities from 2010 onward. By early 2013, the group was conducting dozens of deadly attacks a month inside Iraq and had begun operations in neighboring Syria. In April 2013, Abu Bakr al Baghdadi announced his intent to merge his forces in Iraq and Syria with those of the Syria-based, Al Qaeda affiliated group Jabhat al Nusra (Support Front), under the name of the Islamic State of Iraq and the Levant (ISIL/ISIS). Jabhat al Nusra and Al Qaeda leaders rejected the merger, underscoring growing tensions among Sunni extremists. 
Al Qaeda leader Ayman al Zawahiri sought to remind IS leaders of previous pledges of loyalty to Al Qaeda made by deceased IS figures, but IS leaders rejected his claims. Al Qaeda's general command issued a statement disavowing the Islamic State in early 2014. Islamic State leaders declared that their group "is not and has never been an offshoot of Al Qaeda," and said that since they viewed themselves as a sovereign political entity, they had given leaders of the Al Qaeda organization deference over time rather than full pledges of obedience.
Declaration of Caliphate
In June 2014, Islamic State leaders declared their reestablishment of the caliphate ( khilafa , lit. succession to the prophet Mohammed), dropped references to Iraq and the Levant in their name, demanded the support of believing Muslims, and named Abu Bakr al Baghdadi as caliph and imam (leader of the world's Muslims, Figure A-2 ). IS leaders have highlighted Baghdadi's reported descent from the Quraysh tribe—the same tribe as the Prophet Muhammad—as well as his religious training, as qualifications for his position as caliph. Islamic State spokesman Abu Muhammad al Adnani describes Baghdadi as, "the mujahid shaykh, the learned, the active, and the devout, the warrior and the renewer, the descendant of the Prophet's house." The group cites its implementation of several of the historical requirements of the caliphate/imamate as further grounds for the religious legitimacy of its actions.
U.S. officials suggest that the concept of reviving or renewing the caliphate has attracted some followers to the Islamic State organization, Baghdadi's self-appointment as caliph has been rejected by many Islamic scholars and has yet to inspire mass political support. In one open letter to Baghdadi, a group of prominent Muslim scholars questioned the legitimacy of his appointment, asking "Who gave you authority over the ummah (community of believers)? Was it your group? If this is the case, then a group of no more than several thousand has appointed itself the ruler of over a billion and a half Muslims." Rather than debate Baghdadi's credentials, most Muslim critics simply reject the entire premise of an Islamic State-led caliphate. In particular, they condemn the group's unilateral announcement of a caliphate without consultation or consensus in the broader Muslim community. 
Some jihadist groups, including Al Qaeda, also have rejected Baghdadi's appointment as caliph, arguing that he is simply another military commander and is owed no special loyalty. Al Qaeda leaders Osama Bin Laden and Ayman al Zawahiri viewed the late Taliban leader Mullah Omar as the rightful leader of faithful Muslims and pledged loyalty ( bay'a ) to him, although their views about the wisdom and legitimacy of declaring a caliphate under his leadership or Al Qaeda's differ from those of the Islamic State. In the wake of Mullah Omar's death, Zawahiri has pledged loyalty to his successors, first to the late Mullah Akhtar Mansoor and then to Mawlawi Haibatullah Akhundzada, urging other Muslims to do so. The apparently limited appeal of Al Qaeda and Islamic State demands for leadership recognition suggests that their violent agenda remains popular only among a relatively small, if dangerous, minority of the world's Sunni Muslims. 
Appendix B. IS Affiliates and Adherents
Since 2014, some armed groups have recognized the Islamic State caliphate and pledged loyalty to Abu Bakr al Baghdadi. Groups in Yemen, Egypt, Algeria, Saudi Arabia, Libya, Afghanistan, and Nigeria have used the Arabic word " wilayah " (state/province) to describe themselves as constituent members of a broader IS-led caliphate. The implications of such pledges of loyalty to the Islamic State on groups' objectives, tactics, and leadership structures appear to vary and may evolve. The Trump and Obama Administrations have considered groups and individuals associated with the Islamic State and participating in hostilities against the United States or its coalition partners to be legitimate military targets pursuant to the 2001 Authorization for the Use of Military Force against Al Qaeda, subject to executive branch discretion. 
As of 2018, experts consider the following IS adherents to be the most significant and capable:
The Islamic State in Egypt (IS-SP)
Terrorists based in the Sinai Peninsula (the Sinai) have been waging an insurgency against the Egyptian government since 2011. While the terrorist landscape in Egypt is evolving and encompasses several groups, the Islamic State's Sinai Province affiliate (IS-SP) is known as the most lethal. The group is designated as a Foreign Terrorist Organization pursuant to Section 219 of the Immigration and Nationality Act (8 U.S.C. §1189) and is listed as a Specially Designated National (SDN) by the U.S. Department of the Treasury's Office of Foreign Assets Control (OFAC).
The State Department has stated that IS-SP has used the "under-governed safe haven" found in parts of Egypt's Sinai region to plan attacks both in the Sinai and in mainland Egypt. It has claimed credit for destroying Metrojet Flight 9268, which exploded in mid-air over the Sinai Peninsula on October 31, 2015, killing all 224 passengers aboard. Two years later, on November 24, 2017, IS-SP gunmen launched an attack against the Al Rawdah mosque in the town of Bir al Abed in northern Sinai. That attack killed at least 305 people, making it the deadliest terrorist attack in Egypt's modern history. IS-SP also has targeted Coptic Christians living in northern Sinai. In December 2017, IS-SP attempted to assassinate the Egyptian Ministers of Defense and Interior at the El Arish International Airport in northern Sinai. The group is estimated to have between 800 and 1,200 fighters in the Sinai Peninsula and affiliated cells in the Nile Valley.
In February 2018, the U.S. State Department designated ISIS Egypt as a Specially Designated Global Terrorist group (SDGT) under Section 1(b) of Executive Order (E.O.) 13224. In announcing the designation, the State Department noted that "In May 2017, ISIS announced that ISIS-Egypt was a distinct entity from the FTO and SDGT group ISIS-Sinai Province. ISIS-Egypt has claimed responsibility for numerous attacks in Egypt; in December 2016, for example, the group bombed Cairo's Coptic Christian cathedral, killing 28 people." See, U.S. Department of State, State Department Terrorist Designations of ISIS Affiliates and Senior Leaders, Media Note, Office of the Spokesperson, February 27, 2018.
On February 9, 2018, the Egyptian military launched a campaign, dubbed "Operation Sinai 2018." At the onset of operations, perhaps as many as 42,000 Egyptian troops reportedly were stationed in the Sinai to combat IS-SP. According to one Egyptian media report citing official Egyptian military statements, as of late May 2018, the total number of those killed since the operation began in February 2018 has reached more than 300, including at least 37 Egyptian military personnel. In April 2018, the Egyptian military announced that it had killed Nasser Abu Zaqoul, the purported head of IS-SP.
The Islamic State in Libya (Wilayah Libya/Tarabalus/Barqa)
Supporters of the Islamic State (IS) in Libya announced three affiliated wilayah (provinces) corresponding to the country's three historic regions— Wilayah Tarabalus in the west, Wilayah Barqa in the east, and Wilayah Fezzan in the southwest in 2014 and 2015. Nevertheless, the group does not appear to have created corresponding organizational infrastructure to back its claims, and current operational claims from the group are consistently released in the name of Wilayah Barqa or Wilayah Libya . In July 2018, United Nations reporting citing Member State information estimated that the group has 3,000 and 4,000 members and "still has the capacity to launch significant attacks within Libya and across the border." 
In 2015, U.S. military officials estimated the number of IS supporters in Libya at approximately 3,500 fighters, and later estimated that figure had grown to as many as 6,000, among a much larger community of Libyan Salafi-jihadist activists and militia members. In February 2016, the U.S. intelligence community described the IS presence in Libya as "one of its most developed branches outside of Syria and Iraq," and said the group was "well positioned to expand territory under its control in 2016." 
Such expansion was prevented after the group's stronghold in the central coastal city of Sirte came under siege in May and June 2016 by fighters from the nearby city of Misrata and neighboring towns. IS members in Sirte had previously tried and failed to impose their control on the eastern city of Darnah, but were met with resistance from other armed Islamist groups. IS losses in and around Sirte during the latter half of 2016 were facilitated by a U.S. military campaign (Operation Odyssey Lightning). U.S. assessments stated that by the end of 2017, IS elements in Libya "were in a position to carry out only local-level operations."
As of May 2017, IS-Libya was reported to have approximately 500 fighters, down from 6,000 members in early 2016. Nevertheless, supporters of the group remain active and carry out attacks against militia and security forces in eastern and western Libya adjacent to the group's apparent core area of operation in remote central Libya. According to July 2018 U.N. reporting, "cells persist around Tripoli, Misrata and Sabratah in the west, with a substantial presence in southern Libya around Ghat and Al Uwainat, and Ajdabiya and Darnah in the east."
In November 2015, the U.S. military conducted an airstrike thought to have killed the Iraqi leader of IS operations in Libya, the first such U.S. strike on IS operatives outside of Syria and Iraq. A February 2016 U.S. strike on the western Libyan town of Sabratha targeted an IS-camp and killed dozens of IS fighters, including many from Tunisia. Islamic State supporters in Libya are designated as a Foreign Terrorist Organization pursuant to Section 219 of the Immigration and Nationality Act (8 U.S.C. §1189) and are listed as a Specially Designated Global Terrorists (SDGT) by the U.S. Department of the Treasury's Office of Foreign Assets Control (OFAC).
The Islamic State in Nigeria (West Africa Province, Wilayah Gharb Afriqiyya)
This northeast Nigeria-based Sunni insurgent terrorist group is widely known by the name Boko Haram ("western education is forbidden") and was formerly known as Jama'a Ahl as-Sunna Li-da'wa wa-al Jihad ("People Committed to the Propagation of the Prophet's Teachings and Jihad"). In 2015, its leadership pledged allegiance to the Islamic State, and renamed itself as the Islamic State's West Africa Province (aka ISWAP, ISIS-WA, hereafter IS-WA). Boko Haram subsequently split into two factions, and in August 2016, IS leadership recognized the leader of the offshoot group, Abu Musab al Barnawi, as IS-WA's new wali ("governor"). Many observers, including the U.S. government, now refer to the original faction as Boko Haram and Barnawi's as IS-WA. Both pose an ongoing security threat in Nigeria and the surrounding Lake Chad Basin region. 
More than 15,800 deaths have been attributed to Boko Haram since 2011 (more than 6,500 in 2015 alone), and more than 2 million people have been displaced by related violence, which spread into neighboring Cameroon, Chad and Niger in 2015. The group threatens civilian, state and international targets, including Western citizens, in the region; in 2011 it bombed the United Nations building in Nigeria's capital, Abuja. Reports suggest that Boko Haram and IS-WA operate in distinct but overlapping areas of northeast Nigeria and the surrounding region, with IS-WA appearing to be based near Lake Chad and the Nigeria-Niger border. The groups appear to use different tactics (see U.N. Document S/2017/35), with Boko Haram continuing to deploy women and children as suicide bombers and IS-WA more often focusing on military targets. U.S. government assessments stated that Boko Haram and IS-WA carried out hundreds of attacks in Nigeria in 2017, using suicide bombers, IEDs, raids, ambushes, and kidnappings. 
The State Department designated Boko Haram and a splinter faction, Ansaru, as Foreign Terrorist Organizations pursuant to Section 219 of the Immigration and Nationality Act (8 U.S.C. §1189) in 2013. It similarly so designated ISIS-WA in February 2018. Counterterrorism cooperation with Nigeria has been constrained by various factors. U.S. counterterrorism assistance to the Lake Chad Basin countries has grown substantially since 2014, and the region has been a priority for Department of Defense-funded counterterrorism programs. 
The Islamic State in the Greater Sahara
The Islamic State in the Greater Sahara (IS-GS) is an offshoot of the Algerian-led regional network Al Qaeda in the Islamic Maghreb (AQIM). Based along the Mali-Niger border, IS-GS was formed when leader Adnan Abu Walid al Sahrawi (alt: Abou Walid Sahraoui) pledged allegiance to the Islamic State in May 2015; Islamic State leadership acknowledged the pledge in October 2016. Al Sahrawi, reportedly born in the disputed territory of Western Sahara, was previously a prominent figure in an AQIM splinter faction known as the Movement for Unity and Jihad in West Africa. In May 2018, the U.S. government listed IS-GS (aka ISIS-GS) and Al Sahrawi as Specially-Designated Global Terrorists subject to U.S. sanctions. 
IS-GS has claimed several attacks, notably including an ambush of U.S. Special Operations Forces in western Niger in October 2017 in which four U.S. soldiers were killed. The group is also rumored to be holding a U.S. civilian who was kidnapped in Niger in 2016, although it has made no public claim to that effect. Otherwise, the group has focused on local targets, and many analysts assess its activities to be primarily driven by grievances among its rural Malian and Nigerien recruitment base, fueled by ethnic conflicts as well as patterns of state neglect and abuse. U.N. sanctions monitors reported in mid-2018 that IS-GS members maintained ties with AQIM's Mali-based network, and that both groups shared "the goal of destabilizing the Sahel and any normalization of life there, to maintain freedom of movement in the north [of Mali] and access to smuggling routes." Assessments of the group's size have varied; at least 50 militants reportedly participated in the October ambush in Niger, and recent media accounts estimate several hundred combatants total.
The Islamic State-Khorasan Province (ISKP, Wilayah Khorasan)
ISKP (also referred to as Islamic State-Khorasan or ISK), is an increasingly prominent actor in the conflict in Afghanistan and a major target of U.S. operations there. The group was originally made up of disaffected Taliban and other fighters who declared allegiance to IS as early as 2013; the Islamic State officially announced ISKP as its Afghan affiliate in January 2015. The group was designated as a Foreign Terrorist Organization pursuant to Section 219 of the Immigration and Nationality Act (8 U.S.C. §1189) and listed as a Specially Designated Global Terrorist (SDGT) in January 2016.
The group has long been concentrated in eastern Afghanistan, particularly Nangarhar province, but established operational capabilities in the north by early 2017. The senior ISKP leader in northern Afghanistan (himself a former Taliban commander) was killed in a U.S. airstrike in April 2018. In announcing the strike, NATO described Jowzjan, the northern province where he was killed, as "the main conduit for external support and foreign fighters from Central Asian states into Afghanistan." A July 2018 U.N. report expanded on that assessment, saying that "significant numbers [of foreign fighters] have made their way to Afghanistan" from Syria and Iraq and that several foiled attacks in Europe originated from ISKP. 
While U.S. commanders estimated in March 2017 that U.S. and Afghan military efforts had reduced ISKP strength to around 700 fighters, ISKP now boasts 3,500 to 4,000 militants according to U.N. and other estimates. ISKP leader Hafiz Saeed Khan (a former member of the Pakistani Taliban) was killed in a U.S. strike in July 2016; successors Abdul Hasib and Abu Sayed were killed in in April and July 2017, respectively. 2017 saw intense fighting against ISKP; as many as half of the 14 U.S. combat casualties that year occurred in anti-ISKP operations. The Taliban (condemned as an "apostate movement" by IS) has also targeted ISKP; a large contingent of ISKP fighters surrendered to Afghan forces in August 2018 after being defeated in a Taliban offensive. ISKP has claimed responsibility for a number of large-scale urban attacks against civilians, including multiple bombings targeting Afghanistan's Shia minority. In June, Inspectors General oversight reporting stated that "ISIS-K remained a deadly threat in northeast Afghanistan and in Kabul, even after an intense U.S. and Afghan air and ground campaign against the terrorist group."
The Islamic State in Yemen (Wilayah Al Bayda/Aden-Abyan)
In Yemen, where an ongoing conflict has continued since 2015, various affiliates of the Islamic State (collectively referred to by the U.S. government as ISIS-Y) have targeted government forces in Aden and certain religious factions using suicide bombers, vehicle-borne suicide bombs, and improvised explosive devices (IEDs). Militants who claim allegiance to the Islamic State have taken advantage of the war to repeatedly bomb mosques known for attracting worshippers of Zaydi Islam, an offshoot of Shia Islam (with legal traditions and religious practices which are similar to Sunni Islam). Islamic State terrorists have targeted supporters of the Houthi Movement, a predominately Zaydi armed militia and political group that aims to rule wide swaths of northern Yemen and restore the "Imamate," or Zaydi-led monarchical rule that intermittently governed northern Yemen from 893 AD to 1962. The Houthis are currently at war with a coalition of predominately Sunni Arab states led by Saudi Arabia, and the Islamic State may see this war as an opportunity to increase sectarian hatred in Yemen. Though wracked by war, Yemen has not traditionally had the same kind of sectarian animosity as other Arab states such Iraq and Lebanon. 
The group was designated as a Foreign Terrorist Organization pursuant to Section 219 of the Immigration and Nationality Act (8 U.S.C. §1189) and listed as a Specially Designated Global Terrorist (SDGT) in May 2016. In October 2017, the U.S. Treasury imposed sanctions on several individuals who are leaders and/or financiers of Islamic State affiliates in Yemen. U.S. government assessments stated that IS-Y attacks increased in late 2017. In October 2017, the U.S. military reportedly launched its first air strike against ISIS-Y when it targeted a training camp in Al Bayda governorate. 
The Islamic State in the Caucasus (Wilayah Kawkaz)
The Islamic State recognized Wilayah Kawkaz in June 2015 after IS supporters purportedly drawn from several predominantly Muslim Russian republics in the Caucasus pledged allegiance to Abu Bakr al Baghdadi. Reports suggest that commanders once affiliated with the Al Qaeda-aligned Islamic Emirate of the Caucasus, established in 2007 and declared a terrorist organization by the United States in 2011, make up the leadership of the IS-affiliated organization. The group was designated as a Foreign Terrorist Organization pursuant to Section 219 of the Immigration and Nationality Act (8 U.S.C. §1189) and listed as a Specially Designated Global Terrorist (SDGT) in September 2015. 
Russian officials claimed to have killed the emir of Wilayah Kawkaz in December 2016. Foreign fighters from Russia reportedly made up an influential component of the Islamic State's now decimated fighting force in Iraq and Syria, and late IS leader Abu Omar al Shishani may have helped cultivate deeper ties between IS forces and individuals in the North Caucasus.
The Islamic State in Saudi Arabia (Wilayah Najd/Hijaz/Haramayn)
IS leaders in Syria and Iraq have threatened the kingdom's rulers and state clerics directly and called on the group's supporters in Saudi Arabia to attack Shia Muslims, Saudi security forces, and foreigners. IS supporters have claimed responsibility for several attacks in the kingdom since 2014, including suicide bombing attacks on Shia mosques in different parts of the country and attacks targeting Saudi security forces. In June 2015, an IS-affiliated Saudi suicide bomber blew himself up in a Kuwaiti mosque, killing more than two dozen people and wounding hundreds. Saudi officials have arrested more than 1,600 suspected IS supporters and claim to have foiled several planned attacks. U.S. diplomatic facilities closed temporarily in March 2015 in connection with threat information, and in 2016 an IS suicide bomber attacked the U.S. Consulate in Jeddah. U.S. officials continue to warn of the potential for attacks on U.S. persons and facilities in the kingdom, along with other Western and Saudi targets. The Islamic State in Saudi Arabia and one related individual are listed as Specially Designated Global Terrorists (SDGT) by the U.S. Department of the Treasury's Office of Foreign Assets Control (OFAC).
The Islamic State arguably poses a unique political threat to Saudi Arabia in addition to the tangible security threats demonstrated by a series of attacks and arrests inside the kingdom since late 2014. IS leaders claim to have established a caliphate to which all pious Sunni Muslims owe allegiance, directly challenging the legitimacy of Saudi leaders who have long claimed a unique role as Sunni leaders and supporters of particular Salafist interpretations of Sunni Islam. IS critiques of Saudi leaders may resonate with some Saudis who have volunteered to fight for or contributed on behalf of Muslims in several conflicts involving other Muslims over the last three decades. In August 2018, IS leader Abu Bakr al Baghdadi called on Saudis to rise up and disregard arguments that security is preferable to unrest and infighting. He further alleged that the Saudi government's social reform plans are a plot to "Westernize and Germanize" Muslims and destroy their religion and beliefs. Saudi leaders argue that it is the Islamic State that lacks legitimacy and threatens to bring violence to Saudi society. Some Saudi observers in 2014 compared the group's ideology to that of other violent, deviant groups from the past and present.
The Islamic State in East Asia (Wilayah Sharq Asia, ISIS-Philippines)
Areas in the southern Philippines where the government has failed to assert full control largely due to decades-long Muslim separatist insurgencies have provided breeding grounds for extremist groups and Islamic State affiliates. In recent years, Islamist militants from Indonesia, Malaysia, and outside the region also have gone to western Mindanao and the Sulu Archipelago. ISIS-Philippines (ISIS-P), also known as Daulah Islamiyah, comprises several groups, including branches and remnants of the Abu Sayyaf Group (ASG), the Maute Group, the Bangsamoro Islamic Freedom Fighters, and Ansuar al-Khalifa Philippines. 
With U.S. military assistance, the Philippine Armed Forces (AFP) eroded the strength of the ASG, one the oldest and most established indigenous terrorist organizations in the Philippines, reducing it from 1,000-2,000 fighters in 2002 to about 300-400 in 2013. By 2015, however, a combination of factors – including the withdrawal of the U.S. Joint Special Operations Task Force–Philippines (JSOTF-P), the collapse of a peace agreement between the Philippine government and the Moro Islamic Liberation Front (MILF), and the rise and then difficulties of the Islamic State in the Middle East – fueled a resurgent Islamist terrorist threat in the Philippines. In May 2017, the Maute Group and other Filipino Islamist extremist organizations that had pledged allegiance to IS, along with dozens of foreign fighters, laid siege to Marawi, the capital of Lanao del Sur province. When the Philippine military retook the city after five months, in October 2017, the conflict had resulted in the deaths of nearly 900 militants, over 150 AFP troops and roughly 50 civilians, as well as the destruction of much of the city. 
The Philippine military has continued to engage in "low-level clashes" with ISIS-P, whose numbers dropped to an estimated 200 fighters during the battle for Marawi in 2017, but which may be rebounding. Since late 2017, Islamist extremist groups reportedly have regrouped and begun to attract hundreds of new followers. The ASG has sustained itself economically through ongoing criminal activities such as kidnapping for ransom, extortion, and drug trafficking. Other sources for financing for ISIL-P have included IS funding and the looting of banks and homes during the Marawi siege.