The US has screened about 1,200 moderate Syrian rebels to be trained and equipped to battle ISIL in Syria.
The US Congress has authorised $500m to train 5,000 opposition fighters over the next year.
Turkey, Saudi Arabia and Qatar have offered to host training camps, with work expected to get under way as early as March or April.
While their focus is clear, the new US Defence Secretary Ashton Carter also sees other potential benefits.
Addressing the Congress, he said: "The forces that we're supporting there have first and foremost the job ... of defeating ISIL. But I believe that they also need to be creating the conditions for the removal of Assad."
So, nearly four years into the conflict, with a death toll estimated by the UN at more than 220,000, what are the US priorities in Syria, and where do its international allies stand?
Presenter: Martine Dennis
Mario Abou Zeid - a research analyst at the Carnegie Middle East Center.
Mike Lyons - a military analyst and senior fellow at the Truman National Security Project.
Lama Fakih - a researcher at Human Rights Watch who focuses on Syria.
Source: Al Jazeera