From the Document: "Since 2011, conflict between the government of Syrian President Bashar al Asad and opposition forces seeking his removal has displaced roughly half of the country's population and killed over half a million people. Five countries operate in or maintain military forces in Syria: Russia, Turkey, Iran, Israel, and the United States. The United States seeks a negotiated political settlement to the Syria conflict and the enduring defeat of the Islamic State (IS, aka ISIS/ISIL). Challenges for U.S. policymakers include responding to threats posed by IS remnants and detainees, countering groups linked to Al Qaeda, facilitating humanitarian access, and managing Russian and Iranian challenges to U.S. operations in Syria."
CRS In Focus, IF11930
Congressional Research Service: https://crsreports.congress.gov/