President Donald Trump's national security adviser is calling on Russia to re-evaluate its support for Syrian President Bashar Assad, leaving open the possibility of additional U.S. military action against Syria.
In an interview, H.R. McMaster pointed to dual U.S. goals of defeating the Islamic State group and removing Assad from power.
McMaster says Russia will have to decide whether it wanted to continue backing a "murderous regime" as Trump weighed next steps after ordering airstrikes last week.
He also says Russia should be asked how it didn't know that Syria was planning a chemical attack since it had advisers at the Syrian airfield.
