Since 2014, the United States and a coalition it leads have partnered with a politically diverse set of Kurdish groups to combat the Islamic State organization (IS, also known as ISIS/ISIL or by the Arabic acronym Da'esh ). Coalition-backed Kurdish forces have reversed IS advances in some parts of Iraq and Syria and have taken control of some previously IS-controlled territory. Coalition air support for Kurdish fighters is provided primarily from bases in Iraq, Turkey, and Arab Gulf states. U.S. officials have praised Kurdish fighters as some of the most effective ground force partners the coalition has in Iraq and Syria. Their effectiveness may partly stem from a measure of Kurdish political and military cohesion—relative to other groups—that predates the ongoing conflicts in both countries. Yet, Kurdish military success in both states has complicated U.S. efforts to partner with the Iraqi and Turkish governments, largely because of the boost such success apparently has given to the political ambitions and regional profiles of various Kurdish groups. Efforts by the United States to address its state partners' concerns could fuel uncertainty among Kurdish groups about the terms and durability of U.S. support. In Iraq, the U.S. military has worked with fighters who come under the official authority of the Kurdistan Regional Government (KRG) (see Figure 1 ). In Syria, U.S. forces have partnered with fighters from or allied with the Democratic Union Party (PYD)/People's Protection Units (YPG) (see Figure 2 ). As of December 2016, U.S. partnering with these forces is focusing on and around the key IS-controlled cities of Mosul (Iraq) and Raqqah (Syria). As Administration officials and Members of Congress assess how to reconcile U.S. coordination with Kurdish groups with overall U.S. objectives, their considerations include: The extent to which Kurdish groups should be involved in military operations and post-conflict security in areas with predominantly Sunni Arab or other non-Kurdish populations. The likely effects of U.S. military support for Kurdish groups in Iraq and Syria on state cohesion and political compromise among varying ethnic, sectarian, and ideological groups. Whether and how the coalition's strategic priorities might come into conflict with Kurdish groups' possible goals to (1) maximize their control over territory and resources and (2) reduce or eliminate potential threats (either from rival Kurds or non-Kurds). Questions of leverage between the United States and Kurdish groups, given how they depend on one another for their success and how they each manage relations with other actors—such as the Syrian and Iraqi governments, Turkey, Russia, and Iran. The nature of relationships among Kurdish groups, including the Kurdistan Workers Party (PKK), a U.S.-designated terrorist organization. Legal authorities enacted by Congress and the President permit the Administration to provide some arms and some anti-IS-related funding for Iraq and Syria to Kurdish groups under certain conditions, as discussed below. In April 2016, U.S. officials announced that they would provide more than $400 million to pay and otherwise sustain Iraqi Kurdish fighters with the consent of the Iraqi government. Such support is being drawn from Defense Department-administered funds Congress has appropriated in recent years for countering the Islamic State organization in Iraq. The Obama Administration has requested additional funds to counter the Islamic State organization for FY2017, and Congress may choose to authorize and appropriate anti-IS funding in general terms and/or specifically for various Iraqi forces—including Kurdish groups. Iraqi Kurdish fighters number approximately 160,000, including regular peshmerga and elite forces such as the Zeravani. Prior to the 2014 outbreak of conflict against the Islamic State, these forces had primarily been serving as internal security providers. Of these forces, about 40,000 peshmerga fight in nominally integrated KRG brigades, with the remainder loyal to one of the two main Iraqi Kurdish political groups: the Kurdistan Democratic Party (KDP) or the Patriotic Union of Kurdistan (PUK). According to various open sources, the U.S.-led coalition has trained several thousand peshmerga to participate in anti-IS operations. The general U.S. practice in supplying arms to Iraqi Kurdish peshmerga forces, dating from before Operation Inherent Resolve (OIR), has been to do so either via Iraq's central government or with its express approval. On July 7, 2015, Secretary of Defense Ashton Carter testified to the Senate Armed Services Committee that the United States and other countries "basically convey" weapons directly to the Kurds with Iraqi government approval. Various NATO countries reportedly have directly provided or committed to provide some weapons—including anti-tank missiles and transport helicopters—and non-lethal equipment to peshmerga to augment the Kurds' aging core arsenal of largely Soviet-era small arms and armored vehicles. Notwithstanding the equipment received by peshmerga commanders from various sources, KRG leaders have complained about a lack of heavy weaponry for attack against IS forces from longer ranges. In April 2016, U.S. military officials provided information showing that the U.S.-led coalition was in the process of providing additional equipment to the peshmerga in preparation for anti-IS operations in and around Mosul, including Mine Resistant Ambush Protected (MRAP) armored personnel carriers, anti-tank weapons, mortars, and light arms and ammunition. The Administration allocated $353.8 million for Iraqi Kurdish forces in FY2015 from the $1.6 billion Iraq Train and Equip Fund (ITEF.) Reportedly, Iran and Russia also supply the peshmerga. According to one analyst, Iran has been a major provider of artillery to the peshmerga, "especially BM-14 and BM-21 truck mounted rocket launchers." Russian officials disclosed in early 2016 that they have provided arms to the KRG with Iraqi government approval, including anti-aircraft autocannons. U.S. military trainers and advisors have been based in KRG-controlled areas (along with other areas in Iraq) since 2014, and the U.S. government has acknowledged that advisors have periodically engaged in direct action missions in both Iraq and Syria. More than 5,000 U.S. military personnel are deployed throughout Iraq. Some regional media outlets have speculated that the United States and KRG have secretly agreed to the establishment of enduring U.S. military bases within KRG-controlled areas, though KRG officials have denied this. In April 2016, the Defense Department announced that the United States would provide more than $400 million in assistance to Kurdish peshmerga in coordination with the Iraqi government. This support is intended to help with monthly installments for peshmerga salaries and food, which were previously in short supply given KRG budget shortfalls discussed below. Funds have been drawn from appropriations for ITEF. Proposed legislation for FY2017 would authorize some amounts for peshmerga and other local forces (see " Enacted and Proposed U.S. Legislation " below). In early 2016, Senators Lindsey Graham (chair of the Senate Appropriations Subcommittee on State, Foreign Operations, and Related Programs) and John McCain (chair of the Senate Armed Services Committee) had called for assistance to pay peshmerga salaries. In response to them, Senator Bob Corker (chair of the Senate Foreign Relations Committee) said that in considering any decision to directly fund the KRG, "you have to take into account you could be encouraging the breaking apart of the country." Various political and budgetary issues within the KRG and between the KRG and the Iraqi central government could complicate the KRG's role in countering the Islamic State. These include: KRG budget difficulties linked to (1) Iraqi central government unwillingness since early 2014 to pay the KRG its 17% share of total Iraqi oil revenue (partly driven by the KRG's independent export since 2014 of oil resources it controls via Turkish ports), (2) lower global oil prices, and (3) increases in military spending since the IS threat clearly emerged in 2014. The limited integration (as mentioned above) of KDP and PUK peshmerga into apolitical KRG units. Disputes within the KRG over the continued rule of Masoud Barzani (head of the KDP) as KRG president after his prescribed term in office expired in August 2015, as well as a significant factional dispute within the PUK. Ongoing tension between the KRG and other Iraqi leaders over the composition of the national cabinet. The potential for a future KRG statehood referendum to exacerbate existing KRG-Baghdad disputes regarding territory, governance, and oil. To date, these issues do not appear to have significantly undermined the KRG's military capacity. Before the U.S. announcement in April 2016 of assistance for KRG fighters, the KRG reportedly was paying peshmerga only once every four months. In July 2016, the United States and the KRG signed a memorandum of understanding (MOU) with Baghdad's approval governing the provision of the assistance referenced in the April 2016 announcement. In September, the Iraqi national government and the KRG tentatively resolved their dispute over the export of and division of proceeds from some of Kirkuk's oil. In December, reports indicated that the non-KDP factions within the KRG were working with a major Shia Arab faction toward a possible compromise for the 2017 budget on oil sharing and peshmerga salaries. At present, U.S. assistance to security forces in Iraq, including to Kurdish and other regional or local forces, is coordinated with and/or channeled through the Iraqi national government. This process reflects U.S. policy since the 2003 invasion of Iraq—a policy whose merit has been vigorously debated by U.S. officials and lawmakers—of promoting Iraq's unity under a non-sectarian national government. The process is also reflective of an overall U.S. legal and policy approach that identifies countries (i.e., national governments) and international organizations as the specified lawful recipients of U.S. security assistance. However, since 2014, some U.S. and international observers have at times criticized the Iraqi Security Forces (ISF)'s performance against the Islamic State. Critics have contended that Iraq's central government has at times failed to direct necessary assistance to local Kurdish and Sunni forces or to adequately constrain some Iran-backed Shia militia forces engaged in the anti-IS fight. Some legislative proposals considered in the 114 th Congress reflected these views and sought to provide authorization for direct U.S. assistance to specific forces in Iraq in addition to ongoing engagement with and support for the ISF. The FY2016 National Defense Authorization Act (NDAA) reported by committee to the House ( H.R. 1735 ) in May 2015 would have required that at least 25% of the $715 million in ITEF funding authorized under Section 1223 of the bill would have been used to directly assist peshmerga and/or various local Sunni security forces without requiring prior approval or consultation with Baghdad. The provision would have explicitly directed the executive branch to consider Kurdish peshmerga and various other subnational forces as the equivalents of "countries." This version sparked considerable national political debate in Iraq, and the direct reference to "countries" was removed by a managers' amendment during floor consideration of the bill. In line with post-2003 U.S. policy regarding Iraq and its constituent geographic, ethnic, and sectarian parts, the Obama Administration expressed concerns that removing the requirement for the Iraqi government to consent to U.S. assistance for Kurds in northern Iraq might undermine Iraq's unity and political cohesion. As mentioned above, by mid-2015, U.S. officials had begun to expedite arms deliveries more to KRG-affiliated forces, probably to some extent in response to Kurdish complaints that the Iraqi central government did not distribute U.S.-provided weapons fairly or quickly enough. In Secretary Carter's July 7, 2015, Senate Armed Services Committee testimony, he said that KRG President Barzani had communicated to him that the delays the KRG had experienced in procuring equipment were no longer occurring. The FY2016 NDAA enacted by Congress and the President in late 2015 ( P.L. 114-92 ) provided an explicit legal basis—previously lacking—for direct U.S. support to Iraqi Kurdish and Sunni forces, but left ultimate discretion on the matter with the President. Section 1223(e) authorized the President to provide arms directly to Kurdish peshmerga (among other regional or local Iraqi forces with a "national security mission") for anti-IS purposes if he determines that the Iraqi government has failed "to take substantial action to increase political inclusiveness, address the grievances of ethnic and sectarian minorities, and enhance minority integration in the political and military structures in Iraq." In a March 2016 report to various congressional committees required by Section 1223(e), the Defense Department and State Department assessed that the Iraqi government had taken meaningful steps toward greater inclusivity and integration of minorities. Additionally, Section 7041(c)(3) of the 2016 Consolidated Appropriations Act ( P.L. 114-113 ) stated that funds appropriated by the act for Iraq under the headings "International Narcotics Control and Law Enforcement" and "Foreign Military Financing Program" "should be made available to enhance the capacity of Kurdistan Regional Government security services and for security programs in Kurdistan." The House Appropriations Committee report ( H.Rept. 114-577 ) accompanying the committee's version of the Department of Defense Appropriations Act, 2017 ( H.R. 5293 ), strongly encourages the Secretary of Defense to "consider the use of all available authorities and funding to build the capacity of the KRG" against the Islamic State. The FY2017 NDAA ( S. 2943 ) enacted in late 2016 extends the authorization to provide funding to peshmerga and other forces with a "national mission" through December 31, 2018. It also extends the authorization to use Foreign Military Financing (FMF)-Overseas Contingency Operations (OCO) funds for loans usable by Iraq for U.S. arms purchases, while adding the requirement that any loan notification submitted to Congress shall include "a detailed summary of the terms and conditions of such loan and an assessment of the extent to which use of the proposed loan proceeds would place special emphasis on the Kurdish Peshmerga, Sunni tribal security forces, or other local security forces, with a national security mission." The FY2017 NDAA conference report ( H.Rept. 114-840 ) explicitly identifies $50 million of the $969.5 million authorized for ITEF as allocated for peshmerga and Sunni tribal security forces in Iraq "for operations in Mosul." The Further Continuing and Security Assistance Appropriations Act, 2017 ( P.L. 114-254 ), enacted in December 2016, appropriated $289.5 million to ITEF as part of OCO funding to "support counter-terrorism operations." This appropriation followed a November 2016 Administration request for the same amount in ITEF/OCO funding for "conditions-based sustainment assistance to the Kurdish Peshmerga through the Government of Iraq, including stipends and other sustainment, training, and equipment." According to the request: This assistance is not only helping the Kurdish Peshmerga to continue the fight, but it is also responding to economic pressures faced by the Kurdistan Regional Government (KRG). Support to KRG and Peshmerga helps enable and assure their cooperation in, and contributions to, the continuing campaign against ISIL. If used for the peshmerga, this $289.5 million would presumably supplement the more than $400 million subject to the July 2016 MOU mentioned above. U.S. loan guarantees often complement or supplement other countries' capacity to borrow from other international actors. In Iraq's case, the International Monetary Fund (IMF) approved a three-year, $5.34 billion loan in July 2016, and KRG leaders have sought assurances that they will benefit from the credit being extended to the Iraqi national government. In August 2016, the Obama Administration requested that FY2017 continuing appropriations legislation include an authorization for a $1 billion sovereign loan guarantee to Iraq from amounts provided within the Economic Support Fund account. H.R. 2028 authorizes the use of FY2017 Economic Support Fund (ESF) money for loan guarantees to Iraq provided That the Secretary of State should obtain a commitment from the Government of Iraq that such government will make available the proceeds of such financing to regions and governorates, including the Kurdistan Region of Iraq, in a manner consistent with the principles of equitable share of national revenues contained in clause "Third" of Article 121 of the Constitution of Iraq: Provided further , That such funds shall be subject to prior consultation with, and the regular notification procedures of, the Committees on Appropriations, except that any such notification shall include a detailed summary of the terms and conditions of such financing and an assessment of the extent to which the proposed financing agreement between the Governments of the United States and Iraq supports the constitutional principles of equitable share of national revenues to regions and governorates, including the Kurdistan Region of Iraq. A FY2017 bill proposed by the House Appropriations Committee would require that "not less than 17 percent of the proceeds" of U.S. guaranteed lending benefit the KRG [Section 7041(c)(3)(A) of H.R. 5912 ]. The FY2017 NDAA conference report requires a joint Defense Department/State Department report on political and military strategies to defeat the Islamic State, including: (1) the military conditions that must be met for ISIL to be considered defeated; (2) the plan for achieving a political transition in Syria; (3) a plan for Iraqi political reform and reconciliation among ethnic groups and political parties; (4) an assessment of the required future size and structure of the Iraqi Security Forces, including irregular forces; and (5) a description of the roles and responsibilities of U.S. allies and partners and other countries in the region in establishing regional stability. The conference report also requires a Comptroller General's report assessing the "United States' and the Government of Iraq's capacities to apply transparency and antifraud mechanisms, accounting and internal controls standards, and other financial management and accountability measures to transfers of cash and other forms of assistance provided to the Iraqi Security Forces, including irregular forces, and other recipients through the Iraq Train and Equip Fund." As the offensive against IS in Mosul proceeds, Defense Department officials state that Kurdish forces are closely involved in military operations surrounding the city. However, according to the Defense Department, as various anti-IS forces coordinate their actions, ISF and local Sunni tribal fighters are expected to take a larger combat and post-conflict security role in Mosul itself than Kurdish forces (or Shia militias), based on factors including: U.S. and Iraqi central government interests in minimizing Kurdish-Arab tensions in Mosul and Kurdish political control over ethnically mixed areas, given concerns about (1) Iraqi political unity and (2) human rights practices in areas currently under Kurdish control. For example, the peshmerga's seizure in June 2014 of most of the disputed province of Kirkuk as the Islamic State overran Mosul complicated ISF-peshmerga cooperation. Apparent Kurdish interests in maintaining control over the largely Kurdish-populated territory they already hold rather than taking military risks in areas largely populated by Sunni Arabs and other non-Kurds. Improvement in non-Kurdish forces' capabilities via training, resources, experience, and U.S. air and ground support. The operations around Mosul have featured an unprecedented level of cooperation between the ISF and peshmerga, including the KRG's willingness to allow the ISF use of and passage through Kurdish-controlled areas. However, as of December 2016, the KDP has steered the KRG to reject a 2017 budget approved by Iraq's parliament and other Kurdish factions that would condition delivery of the KRG's share of the national budget on limits to the KRG's autonomy over oil resources it controls. In November, the Iraqi parliament voted to have the Shia-majority Popular Mobilization Forces (PMF) become part of Iraq's military. Since 2015, about 500 Turkish military personnel based northeast of Mosul near Bashiqa have been training Turkmen, Kurds, and a predominantly Sunni Arab "National Mobilization Force" ( Hashd al Watani , recently renamed the "Ninewa Guard Force") affiliated with former Ninewa province governor Atheel al Nujaifi. Turkish officials assert that a considerable portion of the approximately 3,000 local fighters trained at Bashiqa are taking part in anti-IS operations in the vicinity of Mosul, along with Iraqi security forces and peshmerga. Some reports indicate that these fighters may receive artillery support from Turkey. Baghdad officials have protested to the United Nations Security Council that this Turkish military presence in Iraq is unauthorized. A public dispute between Turkish President Recep Tayyip Erdogan and Iraqi Prime Minister Hayder al Abadi over the Turkish presence and their role in forthcoming Mosul operations escalated in October 2016 after President Erdogan implied that only Sunnis should remain in Mosul after its recapture, and he refused to accept Iraqi government command of Turkish forces or Iraqi conditions on the participation of Turkish troops. Prime Minister Al Abadi has insisted that forces respect Iraqi sovereignty, and some hardline Iraqi Shia groups are describing the Turkish forces as occupiers and threatening to attack them. Turkey remains concerned about the presence and activity in northern Iraq of the PKK as well as the possibility of Iranian-supported Iraqi Shia groups increasing their influence in the area, which was separated from the Ottoman Empire (Turkey's predecessor state) under League of Nations arbitration after World War I. Shia PMF militias have advanced toward the outskirts of the city of Tal Afar, which was home to a mixed Sunni and Shia population of ethnic Turkmen prior to IS forces evicting Shia inhabitants in 2014. Turkey also deployed additional forces to the border crossing at Silopi and threatened to intervene if Shia PMF forces enter Tal Afar and harm its Sunni Turkmen inhabitants. The Turkish forces now at Bashiqa are based on territory controlled by KDP-affiliated peshmerga forces. On October 5, 2016, Vice President Joe Biden spoke with KDP leader/KRG President Barzani and "stressed the importance of ensuring that all military operations in Iraq respect Iraq's territorial integrity and sovereignty." On October 11, the State Department spokesperson repeated that formulation in a daily press briefing and said that "the situation in Bashiqa is a matter for the governments of Iraq and Turkey to resolve. What we support is continued dialogue between them that can lead to a speedy resolution of the matter." In November, Iraqi and Turkish officials exchanged views on a possible resolution to the dispute, with Iraq signaling its openness to the continuing Turkish presence if Iraqi sovereignty over the base is recognized and with Turkey suggesting it would consider withdrawing from the base if the area remains secure in the wake of the peshmerga recapture of the surrounding area. As continuing operations appear likely to drive IS fighters out of northern Iraq more broadly, Turkish officials have expressed concern about the possibility that forces from the PKK might gain greater control in and around areas such as Sinjar. Such heightened PKK control in these areas, or Turkish efforts (possibly taken in conjunction with the KDP) to counter PKK influence there, could further complicate cross-border dynamics that have implications both for the PKK's insurgency inside Turkey and for ongoing contention between Turkey and Syrian Kurdish groups with apparent PKK links (see " Turkey, the PKK, and the Syrian Kurds' Situation " below). According to one source, Iran's Islamic Revolutionary Guard Corps (IRGC) is providing support to the PKK in an effort to weaken Turkey and the KRG. In October 2015, the Administration shifted the focus of its Syria train-and-equip program away from forming new units and toward supporting approved leaders and units already fighting or poised to fight the Islamic State. Some forces from the YPG—estimated by various unofficial sources to range in number from 25,000 to 50,000 —then joined with non-Kurdish (mainly Sunni Arab, with some Christian and Turkmen) units to form an umbrella organization known as the Syrian Democratic Forces (SDF). Shortly thereafter, the U.S. military began airdropping weapons to elements within the SDF and working closely with it. In late 2015, approximately 50 U.S. Special Forces personnel reportedly were deployed in northern Syria primarily in an advisory capacity. In April 2016, President Obama authorized 250 additional U.S. forces, including special operations forces and medical and logistics personnel, to deploy to Syria. Additional forces have reportedly followed, and the President authorized 200 more special operations forces in December 2016. Some of the U.S. personnel interface with SDF units and may also recruit non-Kurdish fighters for these units. One analyst has claimed that anti-IS clans have joined the SDF largely because "the SDF is the single repository for U.S. weapons." In early 2016, reports surfaced that the United States was in the process of establishing or refurbishing two air bases in Kurdish-controlled areas in northern Syria. U.S. Central Command (CENTCOM) denied any suggestion of U.S. control over Syrian airfields, stating that U.S. forces were simply "looking for ways to increase efficiency for logistics and personnel recovery support." When addressing questions about the supply of U.S. arms and participation in military operations, U.S. officials generally emphasize the diverse composition of the SDF, even though the YPG reportedly maintains a predominant role in command decisions and key combat actions. Speaking at a public event in September 2016, General Joseph Dunford, USMC, Chairman of the Joint Chiefs of Staff, said that there are around 14,000 Arabs among the 30,000-strong SDF. The constituent elements of the SDF reportedly remain fluid, with various groups joining or leaving depending on changes in military or political realities. Most reports indicate that the YPG remains relatively lightly armed. Some observations suggest that the YPG's guerrilla-style battlefield tactics rely on significant operational flexibility and a high tempo based on the use of foot soldiers, snipers, machine guns, and self-produced mortars and explosives. Although a YPG official was cited in October 2015 as claiming that the YPG received a U.S. weapons airdrop and would share it with other SDF groups, Secretary Carter countered that the airdrop was delivered to Arab elements of the SDF. The U.S. military has subsequently made hundreds of subsequent resupply deliveries to Arab militias associated with the SDF, and some analysts consider such aid to essentially be for the YPG. A U.S. plan that has reportedly been considered to directly arm Syrian Kurdish groups would provide the YPG with small arms and ammunition, but no heavy (i.e., antitank or antiaircraft) weapons. Reports indicate that U.S. support for the SDF has been limited to small arms given Turkish officials' concerns that anti-tank missiles could be used against Turkey in the future. In September 22 Senate Armed Services Committee testimony, General Dunford agreed with the idea that arming and reinforcing Syrian Kurds could increase the effectiveness of the anti-IS effort and prospects of success in Raqqah. Weapons sources for the YPG presumably include black market purchases and caches seized from the Islamic State and other adversaries. Blogs and social media engaging in unsubstantiated speculation about other possible YPG arms sources reference Iraqi Kurdish groups and the Turkey-originated Kurdistan Workers' Party (PKK). The PKK is a U.S.-designated terrorist organization and foreign narcotics trafficker that is widely viewed as the PYD/YPG's parent organization (see " Turkey, the PKK, and the Syrian Kurds' Situation " below). Because the U.S. military lacks a state partner in Syria, the United States may be more dependent in Syria than in Iraq on Kurdish ground forces. The executive branch has struggled with how to calibrate support for the YPG on one hand and various other Syrian forces on the other. Consequently, a key U.S. objective appears to be to strengthen the YPG's non-Kurdish partners in the SDF so that they can (1) help capture IS-held territory in predominantly Sunni Arab areas, and (2) take primary responsibility for providing security to non-Kurdish populations after territory is taken. Turkey is the NATO country where many anti-IS coalition aircraft are based, and its leaders seek to have influence over outcomes and future order in border areas of the weakened Iraqi and Syrian states. Turkey equates the PYD/YPG with the PKK, and thus strongly opposes U.S. support for the PYD/YPG and is suspicious of support for the SDF. Increased PYD influence and territorial control in northern Syria may be partly fueling conflict in Turkey between the PKK and the Turkish military. The Obama Administration does not equate the PYD/YPG with the PKK as Turkey does. However, a number of sources point to evidence of close and continuing operational and personnel links between the PKK and PYD/YPG. One such source claims that although the PYD and PKK are officially independent, "in practice, Syrian Kurdish PKK cadres with years of service in Qandil (the organisation's northern Iraqi mountain base) [see Figure 1 ] dominate the YPG leadership and are the decision-makers within the self-proclaimed 'autonomous administration'" in Syria. This same source claims that U.S. support for the YPG has encouraged the broader PKK organization to pursue escalation in Turkey. The PKK and its affiliates apparently calculated—perhaps not recognizing that U.S. views would probably reject this calculation—that an upheaval undermining central authority in Turkey could "reshuffle the regional order in the Kurds' favour" without endangering PYD/YPG achievements in Syria. However, one analyst has asserted that the PYD has become distinct in some ways from its "PKK roots." Turkey's military became directly involved in a cross-border military operation in August 2016. The operation (codenamed "Euphrates Shield") features Turkish air and artillery support for Turkish tanks and for ground forces drawn from Syrian Arab and Turkmen units under the umbrella of Free Syrian Army (FSA) opposition to the Syrian regime. Some of these FSA-affiliated units have received external support from state actors seeking the removal of Bashar al Asad. Turkish officials have publicly explained that Euphrates Shield seeks to counter actors that Turkey considers to be terrorists, whether they are affiliated with the Islamic State or the PKK. Operation Euphrates Shield began less than two weeks after the SDF captured the town of Manbij from IS fighters, and one of the Turkish operation's main objectives is to prevent Kurdish fighters within YPG/SDF units from establishing an indefinite presence in Manbij or other areas within the contested territory between the Kurdish-controlled cantons of Afrin (in the west) and Kobane (in the east) (see Figure 2 ). After dislodging IS fighters from the town of Jarabulus and elsewhere along the border between the Kurdish cantons (in some cases via largely uncontested efforts) Turkish-supported forces have clashed with Kurdish-led units in the area, and Turkish airstrikes have targeted Kurdish-controlled positions. Turkey claims that these strikes have killed hundreds of YPG personnel. As of December 2016, Turkish-supported forces appear focused on obtaining control of Al Bab, a key transport hub that has been controlled since 2014 by the Islamic State and is coveted by all parties involved in the ongoing conflict in northern Syria. Turkish President Recep Tayyip Erdogan has said that subsequent Turkish-supported action in Manbij is possible. In August 2016, Vice President Biden called for all Kurdish fighters in Manbij to retreat east of the Euphrates River, and the OIR spokesperson said that this retreat had either occurred or was ongoing as of mid-November. However, Erdogan alleged in late November that PYD/YPG elements remained in Manbij. U.S. officials reportedly assess that Turkish-supported troop numbers might need to increase if Turkey expects to drive military or political outcomes in this area. U.S. forces have provided air, artillery, and special forces support to Turkish-supported forces in their operations against the Islamic State (with the joint effort dubbed "Operation Noble Lance" since September 2016), but U.S. officials have called upon the Turkish-supported forces and the Kurdish-led forces to refrain from fighting one another. The embedding of U.S. forces on both sides could be a way to keep communications open between the two and try to reduce the possibility of armed conflict. However, the OIR spokesperson stated in mid-November 2016 that U.S. forces were not providing airstrikes in support of Turkish operations focused on Al Bab, and that embedded U.S. forces had been decoupled from Turkish-supported forces when it began advancing on Al Bab. He said that Turkey was pursuing these operations "independently and what we'd like to do is continue to work with them to develop a plan where everyone remains focused on Daesh." Some media sources have speculated that the Syrian government (with Russian support) was behind a November 24 airstrike that killed four Turkish special forces personnel near Al Bab, indicating that a number of actors may be concerned about Turkish designs on that strategically important place. As the PYD has extended its de facto political control throughout areas controlled or seized by the YPG, it has sought greater public and international legitimacy. PYD leaders likely hope that the United States, Russia, and other key actors agree that an eventual Syrian political resolution will probably involve some degree of decentralization, as well as a role for the Kurds. The PYD has sought to participate in international talks regarding Syria's political future, but has been excluded to date based in part on objections from Turkey, which has insisted that other Syrian Kurds should participate. Turkey had hosted PYD leader Salih Muslim on multiple occasions prior to the resumption of Turkey-PKK violence in 2015. The PYD still faces some opposition from other Syrian Kurdish groups, and some human rights organizations (as discussed below) have questioned YPG compliance with international laws and norms in areas it controls. Some 2016 media reports have indicated that Syrian Kurds and a council they lead (including Arabs, Turkmen, and Christians) are considering declaring a federal region for the various ethnosectarian groups in areas under de facto PYD control. Along those lines, in September 2016 Syrian Kurdish authorities conducted a census among the population in areas under their control in preparation for eventual elections. In June 2016, one analyst wrote, "While some Syrian opposition groups have attacked the PYD for not doing enough to integrate Arabs, it has also been criticized by other Kurdish parties for doing too much." Although Syrian Kurds have instituted a measure of self-rule with regard to education, other basic services, and even their own representational offices in some foreign countries, they reportedly remain dependent on the Syrian government "to pay the majority of civil-servant salaries, issue high-school and college diplomas, and run the region's airport." Turkey and the KRG have generally closed their borders to goods from PYD-controlled areas of Syria. Beyond Turkey's clear objections to the influence that greater Syrian Kurdish autonomy might have on the aspirations of Turkey's Kurds, a Syrian Kurdish-led federal region would have implications for a number of other stakeholders in Syria's conflict. It could affect the military posture and political aspirations of Syria's government, the Islamic State, various other Sunni groups, and minorities. It could also influence the calculations of outside actors. In a March 17, 2016, daily press briefing, the State Department spokesperson stated U.S. opposition to "self-rule, self-autonomous zones," while expressing openness to a federal system if chosen by the Syrian people. At least one media report indicates that Russia has supported discussing the possibility of granting Syrian Kurds special status within the country, but that the Syrian government has rejected the idea. The Syrian government and the PYD/YPG have been relatively non-belligerent throughout Syria's civil conflict, and some sources have reported that the two have made occasional common cause. But the PYD/YPG has a historically grounded wariness of the Asad regime, and clashes between the two broke out in the city of Al Hasakeh in August 2016. Some reports indicate that the YPG had even received occasional military assistance from the regime, and that Russian forces in Syria had enabled some YPG military actions west of the Euphrates, particularly before Russia and Turkey improved their previously degraded relations (in relation to the Turkish downing of a Russian aircraft in November 2015) in June 2016. Shortly after the anti-IS offensive began against Mosul in October 2016, U.S. officials began publicly discussing imminent operations with partners against IS fighters in and around Raqqah. A November 2016 media report cited U.S. military officials as sketching out a three-phase plan: 1. Preparatory air strikes that have already taken place for months. 2. A campaign to isolate Raqqah from resupply. 3. The direct assault on Raqqah itself. Lt. Gen. Stephen Townsend, Commander Combined Joint Task Force (CJTF)-OIR, has expressed that operations focused on Raqqah are urgent largely because of the coalition's interest in preventing IS fighters (including those fleeing Mosul) from regrouping in Raqqah and carrying out potential external attacks. On November 6, an SDF spokesperson said that the SDF had begun its offensive to isolate Raqqah shortly after receiving a shipment of weapons and ammunition from the U.S.-led coalition. Brett McGurk, the Special Presidential Envoy to the Global Coalition to Counter ISIL, stated that U.S. Special Forces would assist as advisors in the operation (dubbed "Euphrates Rage"). In a November 10 Defense Department briefing, the OIR spokesperson indicated that U.S. forces in the region were providing air support to the SDF—including both YPG and Arab fighters (the Arabs within the SDF are sometimes known as the "Syrian Arab Coalition")—as part of the operations to isolate Raqqah. Operations within Raqqah itself are anticipated to follow, although U.S. military leaders have said that the isolation phase could take "months." One observer opined in late November that statements from U.S. officials hinting at impending operations may be influenced by pressure on these officials to "'accelerate' the fight against ISIS," but "shaping operations in the surrounding countryside will prolong for some time." The timeline may also be affected by the transition from the outgoing Obama Administration to the incoming Trump Administration, as well as the possibility that some of the resources the anti-IS coalition is using for Mosul may be needed for Raqqah. Responding to threats they face in Mosul and Raqqah, as of December 2016, some IS fighters are reportedly relocating to the Syrian province of Deir ez Zor near the Iraqi border. General Dunford's September 22 congressional testimony indicated that the United States has assisted anti-IS forces with planning, logistics, equipment, and training in preparation for a Raqqah operation. Reports based on official statements indicate that the 30,000 to 40,000 of SDF fighters expected to take part in the operations are made up roughly of two-thirds Syrian Kurds (YPG) and one-third Syrian Arabs. Questions remain about the composition of the forces that will be expected to actually seize Raqqah and provide for its post-conflict administration. By U.S. officials' accounts, Kurdish YPG elements of the SDF remain the most numerous and capable, and will feature prominently in the operation. However, General Dunford explicitly stated in his September 22 congressional testimony that Kurdish forces are "not intended to hold Raqqa." In the OIR spokesperson's November 3 briefing, he acknowledged that building up the Arab contingent of the SDF was of particular importance "because we do understand that Raqqah is primarily an Arab city. And … just like the Iraqis have done in Mosul, we do understand that there is a political dimension and a local acceptance dimension to this fight." U.S. military officials have indicated that they view the SDF's previous use of local forces as a model for future operations in and around Raqqah. According to Lt. Gen. Townsend, in various other areas of northern Syria—including the strategically positioned town of Manbij—the coalition and its partners had "recruited forces from the local area that were part of the assault force to liberate that area. And they form the core of the whole force that will stay." It is unclear to what extent local forces are able to secure these smaller areas in northern Syria without a residual YPG presence, and to what extent similar operations might be successful on a larger scale in Raqqah. U.S. officials acknowledge that recruitment, training, and actual operations involving newer local forces will be challenging and potentially time-consuming. Townsend has anticipated that most of the recruiting and basic combat training will be done by existing SDF forces, with the training likely taking place in areas of northern Syria somewhat removed from Raqqah. U.S. advisors would assist with "specialty courses, weapons, leadership courses." The OIR spokesperson, in his November 3 briefing, said that the time period for training is generally not very long, partly because many recruits will have had previous fighting experience. Turkey harbors deep concerns about the U.S.-led coalition's partnering with the SDF, including the YPG elements within it. Turkish President Erdogan and other Turkish officials insist that the coalition abandon its support for the YPG, and propose that Turkish-supported forces could participate with the United States in operations in and around Raqqah. Although Turkish-supported forces in Operation Euphrates Shield have achieved some successes, questions exist about Turkey's willingness and capability to shape political outcomes in Syria via military action and support. In a November 30 Defense Department briefing, the deputy commander of CJTF-OIR (a British major general) said that dialogue would continue with Turkey and other interested parties to "decide on what force is best placed to retake Raqqah." One analysis of different Raqqah operational scenarios indicates that the SDF may be better-positioned than Turkish-supported forces to prosecute the military campaign, but asserts that potentially wider territorial clashes between the two near the Turkish border could detract from anti-IS coalition objectives in Raqqah. It is also unclear to what extent Raqqah and its immediate vicinity is an area of priority for the YPG or Turkey, particularly in light of the ongoing rivalry between the two for Al Bab and Manbij. Direct Turkish involvement in and around the primarily Arab-populated Raqqah could raise concerns regarding ethnic sensitivities and local acceptance similar to those mentioned above regarding possible Kurdish involvement. While Kurdish groups in Iraq and Syria work with the U.S.-led coalition against the Islamic State, various humanitarian and human rights concerns have affected Kurdish-populated communities and the surrounding areas where Kurdish forces have been active. With the assault by U.S.-backed Iraqi forces in Mosul, the largest remaining stronghold of the Islamic State, concerns remain about the humanitarian impact of the operation, including evacuation plans and the protection and assistance of those who flee (or stay) and the possible influx of tens of thousands of internally displaced persons (IDPs) to areas under the control of the KRG. As a result of the conflicts in Iraq and Syria, significant population displacement has occurred and has affected, among other areas, those areas largely populated by Kurds. Certain Kurdish-controlled areas in both countries have become havens for refugees and IDPs. As of December 2016, in connection with various waves of fighting in Iraq since 2014, more than 1 million IDPs (the KRG claims the number is close to 1.8 million)—including Arabs, Kurds, Yezidis, Turkmen, and Assyrian Christians—have sought shelter in the Kurdistan Region of Iraq (KRI). Reportedly, IDPs constitute approximately one-sixth of the current population of the KRI, and in some areas nearly one-third are IDPs. Also as of December 2016, an estimated 225,500 Syrians, most of Kurdish origin, have fled to the KRI. Displaced persons in areas under Kurdish control comprise fewer than one-third of Iraq's total displaced population. Until late 2014, the KRG generally allowed displaced persons to enter and stay in the KRI. At that time, amid growing concerns about the financial implications of sheltering the displaced as their numbers swelled, the KRG imposed restrictions on those allowed to enter the KRI. In order to work, IDPs, refugees, and other foreigners are required to have a security clearance and work permit. Amnesty International also reports that many displaced persons have been denied access to safe areas by Iraqi and KRG authorities. The authorities justify their actions by reference to security concerns, but some observers contend that the measures taken have sectarian and discriminatory undertones. According to the State Department, this is a problem that has mainly impacted IDPs coming into the KRG from elsewhere, but it is unclear how many people may be affected. In discussions with relevant officials, the U.S. Embassy is urging that IDPs have freedom of movement. Although Syrian refugees in the KRI have not been compelled to live in camps, the majority have been sheltered in such facilities with the help of the U.N. High Commissioner for Refugees (UNHCR) and other humanitarian actors. The Ministry of Interior of the KRG is a key government partner. Approximately 30,000 refugees have opted to live in cities instead of camps. For IDPs, there has been less of a coordinated strategy on the provision of facilities and services. The KRG has said that it does not have the financial or technical assistance necessary to register and track all IDPs. IDPs are living in both camp and non-camp settings, with approximately half of these people located in Dohuk province. Some are hosted by communities and municipalities, while others live in rented accommodations or unfinished buildings. The Iraqi government and KRG are responding to the crisis by providing humanitarian aid and coordinating assistance through civil society, local communities, and international organizations. Government leadership of the humanitarian operation is reinforced by mechanisms set up to coordinate assistance: the Joint Coordination and Monitoring Center (JCMC) in Baghdad and the Joint Crisis Coordination Center in Erbil (JCCC). The KRG's ongoing fiscal crisis (see " Political and Budgetary Disputes " above) has been exacerbated by the region's significant population increase and accompanying costs and impacts. Humanitarian experts report that the absorption capacity of the host communities is reaching a critical threshold. Residents are competing with the displaced for jobs and resources, contributing to tensions within communities already struggling with poverty. In 2015, the World Bank and the KRG estimated that the KRG would need $1.4 billion in additional revenue to stabilize the economy. The KRG has requested additional international support, arguing that it has been generous to those fleeing their homes and promoted tolerance and inclusivity throughout the process. Despite these humanitarian response efforts and ISF and Kurdish military gains against the Islamic State, Iraqi civilians (including those living in the KRI) have generally not seen a corresponding improvement in their living situation. Ongoing fighting and the perceptions of danger and uncertainty it fuels continue to create significant displacement, which is difficult to monitor and track. In certain areas, including the KRI, insecurity has severely constrained local, national, and international humanitarian efforts to provide assistance (i.e., food, water, sanitation, health services) and protection to refugees, IDPs, and others affected by conflict. This is especially the case for those thought to be trapped in hard-to-reach areas or in close proximity to front lines. Basic government social services are limited. Health concerns and food insecurity contribute to the vulnerability of millions of civilians. Close to half of those displaced in Iraq are estimated to be children, making emergency education support a significant concern for various actors involved in the humanitarian response. Winter kits and other items like kerosene are also being provided in Dohuk, Erbil and Sulimaniyah, where UNHCR has reached more than 10,000 displaced families with cash assistance since October 2016. Cash assistance has been provided to almost 10,000 Syrian refugee families in those areas as well. As of mid-December 2016, with the Mosul military operation in its third month, more than 100,000 people had been displaced by fighting. Many experts predict that displacement numbers are likely to increase substantially, possibly to 1 million (or more) civilians requiring protection and assistance. The majority of newly displaced families are moving toward areas under the control of the Iraqi Government or the KRG. The Iraqi Government's Ministry of Migration and Displacement (MoMD), the JCCC, and humanitarian partners are working together to increase the capacity to host and support displaced civilians as cold weather sets in. Most of the displaced are being sheltered in UNHCR-supported camps in the area, of which there are six, with another three under construction, and one being planned. In accessible areas around Mosul, there are urgent needs of hundreds of thousands of vulnerable residents, many in areas newly retaken from the Islamic State. As many as 1 million are thought to remain out of reach of humanitarian assistance in Mosul city, with reports of water and food shortages. Trauma injuries have increased amid overall concerns regarding civilian protection. A High Advisory Team (HAT), which includes the Government of Iraq, KRG, militaries and the U.N. Humanitarian Coordinator, meets regularly on humanitarian issues, as do other humanitarian entities to coordinate the Mosul humanitarian response. In northeast Syria, more than 750,000 people—including IDPs and Iraqi refugees—are reportedly in need of assistance in Al Hasakeh governorate (roughly corresponding in location with what some Syrian Kurds regard as the "Jazirah canton" in the northeast part of the country). Iraqi refugees are living in two refugee camps as well as in villages. A Syrian Kurdish leader estimated in May 2016 that approximately 500,000 Syrian IDPs were sheltering in areas of northern Syria broadly controlled by Syrian Kurds. This leader claimed that various international and private organizations have provided some humanitarian assistance to the IDPs, but that such assistance—when available—is largely limited to basic subsistence. Escalations in fighting in conflict-affected areas have increased displacement, while closures of border crossings with Iraq could have a humanitarian impact. In December 2015, the United Nations, along with humanitarian partners, launched the Humanitarian Response Plan (HRP) 2016 for Iraq, which appealed for $861 million, of which $328 million (38%) was identified for the KRI. As of December 21, 2016, the overall Iraq appeal is 83% funded. Since FY2014, U.S. humanitarian assistance for the Iraq response through September 30, 2016, totals $1.1 billion. In addition, the July 2016 U.N. Mosul Flash Appeal seeks $284 million, and as of December 21, 2016, is 92% covered. The United States is the largest donor of humanitarian assistance to the Syria crisis. Since FY2012, it has allocated more than $5.9 billion to meet humanitarian needs using existing funding from global humanitarian accounts and some reprogrammed funding. In keeping with humanitarian principles, U.S. humanitarian assistance is needs-based and can be used countrywide (where access is possible) in Iraq and Syria (including in Kurdish-controlled areas) for the displaced, vulnerable host communities, and others affected by conflict. Therefore, while some assistance is being provided to populations in Kurdish-controlled areas of Iraq and Syria, a breakdown is not available. Protracted conflict and the flow of displaced persons appear to have exacerbated ethnic and sectarian tensions across Iraq and Syria. These developments have heightened international concerns about the vulnerability of civilians to endangerment, dispossession, or other forms of mistreatment or hardship, while also calling into question whether displaced persons will ever be able to return to their places of origin. The Islamic State has committed systematic and widespread violence, with many reported instances of mass executions, kidnappings, systematic rape and sexual violence, and torture. Some other actors—both government and non-state—may also engage in activities endangering or dispossessing civilians. In January 2016, in his report on the U.N. Assistance Mission in Iraq (UNAMI), U.N. Secretary-General Ban Ki-moon stated, "Regrettably, in areas retaken from ISIL, there have been reports of arbitrary arrests, killings, destruction of property, efforts to forcibly change demographic composition and retaliatory violence." Concerns about possible mistreatment by Iraqi and Syrian Kurdish authorities of non-Kurdish populations under their control—possibly even to the level of "war crimes"—have received international attention. A January 2016 Amnesty International report based on satellite photos, field investigations, and eyewitness and victim accounts alleged that KRG-affiliated fighters and other forces acting with their knowledge (YPG, PKK, Yezidi militias) not only displaced Arabs from areas in Iraq captured or recaptured from the Islamic State, and looted their possessions, but destroyed entire villages. A news release accompanying the report's publication stated: Though KRG officials have justified the displacement of Arab communities on grounds of security, it appears to be used to punish them for their perceived sympathies with IS, and to consolidate territorial gains in "disputed areas" which the KRG authorities have long claimed as rightfully theirs. This is part of a drive to reverse past abuses by the Saddam Hussein regime, which forcibly displaced Kurds and settled Arabs in these regions. A second Amnesty International report, Marked With An 'X' I raqi Kurdish Forces' Destruction of Villages, Homes in Conflict with ISIS (November 2016) examines further the conduct of KRG security forces in locations where they have defeated the Islamic State. The report finds a pattern of apparently unlawful demolitions of buildings and homes, and in many cases entire villages, between September 2014 and May 2016, with claims that mostly Arab homes were destroyed. Following the release of the earlier report, KRG authorities subsequently conducted an investigation and reportedly asserted that much of the destruction documented in that report resulted from the U.S.-led coalition's employment of bombs, mortars, and artillery fire against IS positions, as well as from the peshmerga's detonation of IS-planted improvised explosive devices. Additionally, in areas under PYD control in Syria, human rights groups have documented reports of YPG abuses against the PYD's Kurdish political rivals, and of forced displacement of Sunni Arab residents. The possibility of systematic human rights abuses by Kurdish groups could greatly complicate the U.S.-led coalition's heavy reliance on these groups to secure territory in areas of mixed ethnic and sectarian population. It also raises questions about whether and how the coalition's strategic priorities in Iraq and Syria might come into conflict with Kurdish groups' apparent objectives to (1) maximize their control over territory and resources they claim and (2) significantly weaken non-Kurdish groups in their vicinity that are seen as posing potential threats. Some Members of Congress have considered the following issues in assessing policy options related to U.S. support for Kurdish groups fighting the Islamic State organization in Iraq and Syria: Risks that that U.S. equipment provided to Kurdish groups could fall under the control of the Islamic State or other actors actively working against U.S. regional goals. Means for better providing U.S. and international humanitarian assistance to support the needs of displaced persons in the Kurdish-controlled areas of Iraq and Syria. The extent to which the United States can influence the decisions of various Kurdish groups and the extent to which Kurdish decisions may reshape the strategic context in which the United States is pursuing its own goals. The nature of the PYD/YPG's apparent links with the PKK, and related Turkish concerns. Other actors' relationships with various Kurdish groups, including the Syrian and Iraqi governments, Russia, and Iran. Questions reflected in legislative and executive policy discussions as of late 2016 include: What roles should Kurdish ground forces in Iraq and Syria play in U.S.-supported operations, particularly those to take IS strongholds such as Mosul and Raqqah, and in post-conflict administration? To what extent should Congress authorize (or require) the Administration to provide arms or assistance directly to the KRG, the YPG, or forces affiliated with them? To what extent, if at all, should caps or conditions (such as those related to central government approvals, end-use monitoring, human rights practices, or good governance) be placed on arms shipments or assistance? How might other U.S. partners and adversaries view such assistance and respond? How might various types of U.S. military and political support for specific Kurdish or Kurdish-led groups affect (1) prospects for political cooperation or resolution among Kurds and between different ethnic, sectarian, and ideological groups in Iraq and Syria, (2) regional security, and (3) long-term U.S. commitments? What alternatives exist to continued cooperation with Kurdish forces to achieve stated U.S. objectives in the conflict? How should U.S. assistance to Kurdish forces evolve as U.S. objectives for defeating the Islamic State group are achieved? As anti-IS operations continue, U.S. officials appear inclined to embrace the capabilities of various Kurdish ground forces in Iraq and Syria. At the same time, U.S. officials seem to focus on addressing and resolving limitations or complications that may arise from U.S.-Kurdish partnerships. For example, officials may be seeking to leverage and augment the Kurds' military successes by empowering non-Kurdish forces that may be more able to command political legitimacy among local populations in predominantly Sunni Arab areas such as Mosul and Raqqah. U.S. officials may also be looking to minimize disruptions in U.S. relations with other partners—such as the Iraqi and Turkish governments. The future of the U.S.-Kurdish partnership beyond current anti-IS cooperation is unclear and could largely depend on how the current cooperation and its outcomes unfold. Might the present joint efforts translate into a longer-term partnership in a region riven by chronic instability, ethnosectarian tension, and weapons proliferation? Policymakers might conclude that greater U.S.-Kurdish closeness could promote greater stability and political resolution due to some Kurdish groups' active support for U.S. operations in recent decades; general embrace of secular political leadership; and relative prosperity amid the complexities and tribulations of their surroundings. Alternatively, policymakers might conclude that greater U.S.-Kurdish closeness could work against stability in the region due to some Kurdish groups' possible efforts to maximize their influence, wealth, power, and status (potentially including attempts to gain independence or more autonomy) at the expense of non-Kurdish actors; treatment of civilians in areas over which they have recently gained control; and political disputes among themselves, both inside and across national borders. Ultimately, U.S. policy on this question may depend on a number of factors. These include the degree to which the United States is willing to maintain or undertake long-term political or military commitments in the region, and Kurdish groups' value as partners—relative to other state and non-state actors—in contributing to U.S. objectives in that context. 

Summary: Since 2014, the United States and members of a coalition it leads have partnered with a politically diverse set of Kurdish groups to combat the Islamic State organization (IS, also known as ISIS/ISIL or by the Arabic acronym Da'esh). For background information on these groups and their relationships in the region, see CRS In Focus IF10350, The Kurds in Iraq, Turkey, Syria, and Iran, by [author name scrubbed] and [author name scrubbed]. The capabilities of various Kurdish ground forces have advanced some U.S. objectives in connection with ongoing anti-IS operations. At the same time, as these operations increasingly focus on predominantly Sunni Arab areas such as Mosul, Iraq, and Raqqah, Syria, U.S. officials are encouraging Kurdish forces to support and empower the combat and post-conflict administration profile of non-Kurdish forces that may have greater ethnic and political legitimacy with local populations. U.S. officials also seek to avoid having U.S. cooperation with Kurds significantly disrupt U.S. relations with other partners, including the Iraqi central government and NATO ally Turkey in light of those partners' respective concerns and operations on the ground in Iraq and northern Syria. Legal authorities enacted by Congress and the President permit the Administration to provide some arms and some Iraq/Syria anti-IS-related funding to Kurdish groups under certain conditions. In April 2016, the Defense Department announced that it would provide more than $400 million in assistance to pay and otherwise sustain Iraqi Kurdish fighters as part of an ongoing partnership that delivers U.S. assistance to Iraqi Kurds with the consent of the Iraqi national government. Some Members of Congress proposed legislation in the 114th Congress that would have extended or expanded U.S. cooperation with Kurdish groups under certain conditions. This report examines: the roles played by Iraqi Kurdish groups affiliated with the Kurdistan Regional Government (KRG) and by the Syrian Kurdish Democratic Union Party (PYD)/People's Protection Units (YPG) in U.S. and coalition efforts to defeat the Islamic State; interactions Iraqi and Syrian Kurds have with other actors; benefits and challenges the Kurdish role presents for U.S. interests in the region; the outlook for military operations (such as against Mosul in Iraq and Raqqah in Syria) and political outcomes; humanitarian concerns regarding displaced persons in Kurdish-controlled areas, and human rights concerns regarding Kurdish forces' treatment of civilians in areas they capture; specific U.S. policy questions regarding current and future U.S.-Kurdish cooperation; and the broader trajectory of the U.S.-Kurdish partnership. U.S. military trainers and advisors have been based in KRG-controlled areas (along with other areas in Iraq) since 2014. The U.S. government has acknowledged that these advisors have periodically engaged in direct action missions in both Iraq and Syria. Since late 2015, U.S. officials have announced additional "advise and assist" deployments in Iraq and Syria.