"The Islamic State is a transnational Sunni Islamist insurgent and terrorist group that has expanded its control over areas of northwestern Iraq and northeastern Syria since 2013, threatening the security of both countries and drawing increased attention from the international community. There is debate over the degree to which the Islamic State [IS] organization might represent a direct terrorist threat to the U.S. homeland or to U.S. facilities and personnel in the region. [...] In September 10, President Obama announced a multifaceted strategy to 'degrade, and ultimately destroy' the Islamic State organization. The announced strategy is for the United States to lead and expand a multilateral coalition that will undertake direct military action, provide support for partner ground forces in Iraq and Syria, gather and share intelligence and use financial measures to try to progressively shrink the geographic and political space, manpower, and financial resources available to the Islamic State. The Administration and its allies all have ruled out deploying combat forces to either Iraq or Syria. Some assert that the U.S. strategy will attract the support of Sunnis in both Syria and Iraq in a broad effort to defeat the Islamic State. Others assess that the strategy might have minimal effect because local anti-IS forces will not have support from U.S. or other western combat troops. For details on Islamic State operations in Iraq and U.S. policy toward Iraq since the 2003 U.S. invasion, see CRS [Congressional Research Service] Report RS21968, 'Iraq: Politics, Governance, and Human Rights', by Kenneth Katzman. For further 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."
CRS Report for Congress, R43612