The following is the Aug. 21, 2018 Congressional Research Service Armed Conflict in Syria: Overview and U.S. Response.
From the report:
The Syria conflict, now in its eighth year, remains a significant policy challenge for the United States. U.S. policy toward Syria in the past several years has given highest priority to counterterrorism operations against the Islamic State (IS, also known as ISIL/ISIS), but also has included non-lethal assistance to opposition-held communities, support for diplomatic efforts to reach a political settlement to the civil war, and the provision of humanitarian assistance in Syria and surrounding countries. The counter-IS campaign works primarily “by, with, and through” local partners trained, equipped, and advised by the U.S. military, per a broader U.S. strategy initiated by the Obama Administration and modified by the Trump Administration. The United States also has advocated for a political track to reach a negotiated settlement between the government of Syrian President Bashar al Asad and opposition forces, within the framework of U.N.-mediated talks in Geneva. For a brief conflict summary, see Figure 2.
In November 2017, Brett McGurk, Special Presidential Envoy for the Global Coalition to Counter ISIS, stated that the United States was entering a “new phase” in its approach to Syria that would focus on “de-escalating violence overall in Syria through a combination of ceasefires and de-escalation areas.” The Administration supported de-escalation as a means of creating conditions for a national-level political dialogue among Syrians culminating in a new constitution and U.N.-supervised elections. However, since mid-2017, the Asad government has retaken several opposition-held areas of Syria, including ceasefire and de-escalation areas. This appears to have significantly reduced the military pressure on the regime to make concessions to the opposition, with uncertain implications for the outcome of any future political dialogue. Meanwhile, U.S.-backed forces recaptured the group’s self-proclaimed capital at Raqqah in October 2017, and have since retaken most other areas formerly under IS control in eastern Syria.
With the IS threat diminished and the Asad government resurgent, President Trump and Administration officials have sent varying messages about U.S. Syria policy. Officials emphasize that the United States is committed to the enduring defeat of the Islamic State and will not contribute to reconstruction in Asad-held areas unless a political solution is reached in accordance with U.N. Security Council Resolution 2254. Questions remain about the extent to which U.S. forces might remain in Syria and specific U.S. assistance plans. The Administration has ended non-humanitarian U.S. support to opposition-controlled northwest Syria and has obtained foreign contributions to enable the reprogramming of U.S. funds that Congress appropriated to stabilize areas liberated from the Islamic State. The FY2019 National Defense Authorization Act (H.R. 5515) requires the Administration to clarify its Syria strategy and report on current programs in order to obligate FY2019 defense funds for train and equip purposes in Syria.
To date, the United States has directed more than $8.6 billion toward Syria-related humanitarian assistance, and Congress has appropriated billions more for security and stabilization initiatives in Syria and in neighboring countries. The Defense Department has not disaggregated the costs of military operations in Syria from the overall cost of Operation Inherent Resolve (OIR), which, as of March 2018, had reached $23.5 billion. President Trump requested $15.3 billion in additional FY2019 defense funding for OIR. Congress continues to consider proposals to authorize or restrict the use of force against the Islamic State and in response to Syrian government chemical weapons attacks, but has not enacted any Syria-specific use of force authorizations.
Looking forward, Congress may consider the purpose, scope, authorization, and duration of the U.S. military presence in Syria, the U.S role in ensuring a lasting defeat for the Islamic State and other extremists, U.S. investments and approaches to post-conflict stabilization, the future of Syrian refugees and U.S. partners inside Syria, and the challenges of dealing with the Iran- and Russia-aligned Asad government.