The Islamic State (IS) organization is also referred to by its former name—the Islamic State of Iraq and the Levant (ISIL)/Islamic State of Iraq and Syria (ISIS)—and the Arabic acronym Daesh (pronounced "daash," for Dawlat al-Islamiyah f'al-Iraq wa al-Sham ), which translates to the Islamic State in Iraq and the Levant/Syria. Many observers argue that changes in Iraq's political structure as a result of the U.S.-led overthrow of Saddam Hussein helped give rise to the Islamic State. The fall of Hussein's Sunni Arab-dominated government and the ascension to power of the majority Shiite Arab population fueled deep Sunni resentment that continues today. In Syria, the Islamic State has grown in size and strength in part because of the Asad regime's use of Syria's armed forces and Iranian support to try to suppress rebellion by Syria's Sunni Arab majority. The Islamic State's direct ideological and organizational roots 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 (also known as 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 Shiites 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 Shiites 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. 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). 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. 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. Its Muslim critics question its legitimacy and actions. See CRS Report R43612, The "Islamic State" and U.S. Policy , by [author name scrubbed] and [author name scrubbed] for more information. Prior to 2015, the majority of terrorist attacks conducted by IS supporters were in Iraq and Syria. However, in 2015 it appears IS strategy evolved to include pursuing terrorist attacks globally. In this regard, transnational IS terrorist attacks outside of Iraq and Syria may be an instrumental tactic in a broader strategic effort to draw adversaries, including the United States, into larger-scale and more direct conflict. An example of the Islamic State's evolving strategy may be demonstrated in the numerous terrorist attacks occurring in places other than Iraq and Syria with civilian deaths rising to nearly 1,000 since January 2015. See CRS Report R43612, The "Islamic State" and U.S. Policy , by [author name scrubbed] and [author name scrubbed], and CRS Insight IN10209, European Security, Islamist Terrorism, and Returning Fighters , by [author name scrubbed] and [author name scrubbed] for more information. Since 2014, some armed groups outside of Iraq and Syria have recognized the Islamic State caliphate and pledged loyalty to Abu Bakr al Baghdadi. As of late 2015, experts consider IS adherents in Yemen, Egypt, Algeria, Saudi Arabia, Libya, Afghanistan, and Nigeria to be the most significant and capable. These groups 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 Obama Administration has stated that groups and individuals that are associated with the Islamic State and that participate in hostilities against the United States or its coalition partners are legitimate military targets pursuant to the 2001 Authorization for the Use of Military Force against Al Qaeda, subject to executive branch discretion. For more information, see " IS Affiliates and Adherents " in CRS Report R43612, The "Islamic State" and U.S. Policy , by [author name scrubbed] and [author name scrubbed]; CRS Insight IN10199, The Islamic State in Egypt: Implications for U.S.-Egyptian Relations , by [author name scrubbed]; " Armed Islamist Groups and Related Terrorism Threats " in CRS Report RL33142, Libya: Transition and U.S. Policy , by [author name scrubbed]; and CRS Insight IN10242, Nigeria's Boko Haram and the Islamic State , by [author name scrubbed] and [author name scrubbed]. While IS funding streams remain fluid, the group's largest revenue sources appear (based on open-source information) to include oil sales, taxation and extortion, and the sale of looted antiquities. Oil sales initially provided the majority of the group's revenue, but gradually declined as a percentage of overall IS profits due to an extensive campaign of airstrikes by the United States and coalition partners against oil and gas facilities used by the group. U.S. officials have noted that the Islamic State's financial strength depends not only on its income but also on its expenses, and the extent to which it is able to devote its resources to military operations. U.S. officials have stated that the Islamic State's decision to hold and govern territory is a financial burden for the group, and thus a vulnerability that the United States could potentially exploit by diminishing the group's ability to generate and utilize revenue. If the Islamic State cannot afford the expenses associated with governing its territory, some argue that the resulting public backlash would undermine its ability to rule. Targeting the Islamic State's finances is one of five core lines of effort to degrade and defeat the terrorist organization. General John Allen, the recently retired U.S. Special Presidential Envoy for the Global Coalition to Counter ISIL, stated in early 2015 that the United States cannot defeat the Islamic State through military efforts alone, and highlighted the need to deprive the group of access to financial resources. At present, U.S. policy focuses on disrupting IS revenue streams, limiting the group's access to formal financial systems, and imposing sanctions on the group's senior leadership and financial facilitators. The United States also has sought to collaborate with international partners, including through cooperation on financial intelligence collection and analysis. See CRS Report R43980, Islamic State Financing and U.S. Policy Approaches , by [author name scrubbed], [author name scrubbed], and [author name scrubbed] for more information. On September 10, 2014, President Obama announced the formation of a global coalition to "degrade and ultimately defeat" IS. Subsequently, some 60 nations and partner organizations agreed to participate, contributing either military forces or resources (or both) to the campaign. In Brussels in December 2014, these 60 partners agreed to organize themselves along five "lines of effort," with at least two countries in the lead for each: Supporting military operations, capacity building, and training (led by the United States and Iraq); Stopping the flow of foreign terrorist fighters (led by The Netherlands and Turkey); Cutting off IS access to financing and funding (led by Italy, the Kingdom of Saudi Arabia, and the United States); Addressing associated humanitarian relief and crises (led by Germany and the United Arab Emirates); and Exposing IS's true nature (led by the United Arab Emirates, the United Kingdom, and the United States). Coalition participation tends to be fluid, with each country contributing capabilities that are commensurate with their own national interests and comparative advantage. Since August 2015, several coalition participants have changed the roles, missions, and capabilities of the military forces they are applying to counter the Islamic State. Along with the United States, France has been at the forefront of the international coalition conducting military operations against IS in Iraq. Until September 2015, France had ruled out conducting operations in Syria—in part because it did not want to inadvertently support the Asad regime—but changed course due to growing concerns about IS. Following the November attacks, President François Hollande vowed to redouble the military campaign to destroy the Islamic State. Within 48 hours of the attacks, France launched its most aggressive air strikes yet, on the IS stronghold of Raqqa, Syria; the number of French fighter jets conducting airstrikes is to increase from 12 to 38. Hollande has also stressed that he will focus on unifying and bolstering the international military coalition fighting IS. This would include greater cooperation with the United States, Russia, and countries in the region. Russia initiated military operations in Syria in September 2015, but it did not begin robustly targeting Islamic State forces until Russian authorities concluded in mid-November that a "self-made" explosive device had brought down a Russian airliner over the Egyptian Sinai Peninsula on October 31, 2015, killing all 224 passengers on board.