The Islamic State (IS, aka the Islamic State of Iraq and the Levant, ISIL/ISIS) is a transnational Sunni Islamist insurgent and terrorist group that has expanded its control over areas of parts of Iraq and Syria since 2013, threatening the wider region. There is debate over the degree to which the Islamic State organization might represent a direct terrorist threat to the U.S. homeland or to U.S. facilities and personnel in the region. The forerunners of the Islamic State were part of the insurgency against coalition forces in Iraq, and the organization has in the years since the 2011 U.S. withdrawal from Iraq expanded its control over significant areas of both Iraq and Syria. The Islamic State has thrived in the disaffected Sunni tribal areas of Iraq and taken control of some eastern provinces of Syria torn by the civil war. In 2014, Islamic State-led forces, supported by groups linked to ousted Iraqi President Saddam Hussein and some Sunni Arabs, advanced along the Tigris and Euphrates rivers in Iraq, seizing population centers including Mosul, one of Iraq's largest cities. Since then, IS forces have massacred Syrian and Iraqi adversaries, including some civilians, often from ethnic or religious minorities, and murdered hostages, including U.S. citizens. Islamic State offensives in Iraq's Anbar province and against Kurdish enclaves continue. The group's tactics have drawn international ire, and raised U.S. attention to Iraq's political problems and to the war in Syria. On September 10, 2014, President Obama announced a series of actions intended to “degrade, and ultimately destroy” the Islamic State organization. The United States is leading and seeking to expand a multilateral coalition that is undertaking direct military action; providing advice, training, and equipment for partner ground forces in Iraq and Syria; gathering and sharing intelligence; and using financial measures against the Islamic State. The objective of these measures is to progressively shrink the geographic and political space, manpower, and financial resources available to the Islamic State organization. U.S. officials refer to their strategy as “Iraq-first” and “ISIL-first,” amid criticism by some in Congress that more attention should be paid to the civil war in Syria and more effort should be made to oust Syrian President Bashar al Asad. The U.S. desire to show progress against the Islamic State and in the recruitment of regional partners raises questions of whether the U.S. mission and commitment might expand. President Obama has ruled out deploying ground combat forces to Iraq or Syria, but has not ruled out providing forward aircraft controllers, additional military advisors, or other related ground-based military assets. Some experts assert that coalition partners inside Iraq and Syria—Iraqi government forces and select Syrian groups—are too weak to defeat the Islamic State and will eventually require help from U.S. combat troops. Several regional coalition members apparently seek an expansion of the U.S.-led mission to include an effort to oust President Asad of Syria. In December 2014, the 113th Congress provided new authorities and funds for efforts to combat the Islamic State organization in Syria and Iraq in the FY2015 national defense authorization (P.L. 113-291) and consolidated appropriations acts (P.L. 113-235). The 114th Congress is now considering the Administration's FY2016 budget requests and its proposal for authorization for the use of military force against the Islamic State. For details on Islamic State operations in Iraq and U.S. policy toward Iraq since the 2003 U.S. invasion, see CRS Report RS21968, Iraq: Politics, Governance, and Human Rights, by Kenneth Katzman. For information on the Islamic State's operations in Syria, see CRS Report RL33487, Armed Conflict in Syria: Overview and U.S. Response, coordinated by Christopher M. Blanchard.