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. 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. 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.