The emergence of the Islamic State of Iraq and Syria (ISIS) has undermined stability in Iraq, Syria, and the broader Middle East and poses a threat to international peace and security, including to the United States. Since its emergence in Iraq in 2003 as the predecessor organization al Qaeda in Iraq, ISIS has declared branches and established networks in other countries and attracted an international network of supporters, launching acts of violence and terrorism in various countries throughout the world. U.S. officials have noted that, in response to territorial losses on the ground in Iraq and Syria, the threat of ISISinspired attacks may grow, including on Western targets such as the United States. In September 2014, the White House issued the U.S. Strategy to Counter the Islamic State of Iraq and the Levant (ISIL) with the goal to degrade and destroy ISIS through an approach that included working with regional and international partners. The Department of Defense (DOD) reported that it has allocated $10.9 billion for counter-ISIS operations from August 2014-when these operations began-through 2016. The Department of State (State) and the U.S. Agency for International Development (USAID) report having allocated more than $2.4 billion in funding for Iraq, Jordan, Lebanon, and Syria to counter ISIS, respond to and mitigate the Syrian crisis, bolster regional security, and support development programs. State and USAID also report that, separate from U.S. political efforts to counter ISIS, the two agencies have provided more than $1.3 billion in humanitarian assistance to Iraqis in the region since fiscal year 2014 and more than $6.5 billion in humanitarian assistance to Syrians and others in the region affected by the Syrian crisis. Given the importance of this issue as a U.S. national security priority and the level of resources expended to counter ISIS and address humanitarian and other effects related to these efforts, we have identified a number of key issues for the 115th Congress to consider in developing oversight agendas and determining the way forward. Significant oversight will be needed to help ensure visibility over the cost and progress of these efforts. This is a public version of a classified report issued in April 2017.