WASHINGTON >> President Donald Trump’s national security adviser is expressing doubt the U.S. will send more ground troops to Syria. His comments come as rebel forces appear close to launching an assault to capture the Islamic State group’s de facto capital of Raqqa.

H.R. McMaster spoke to ABC’s “This Week” from Afghanistan. He says it “remains to be seen” whether additional troops are needed, but he doesn’t “think so.” McMaster says the U.S. will support its “partner forces” in Syria.

The U.S. has been expected to provide additional arms to the U.S.-backed Syrian Democratic Forces for the Raqqa offensive. But it hasn’t been clear about troops.

Last week, Trump appeared to rule out deeper American military intervention in Syria beyond retaliatory strikes if Syria’s president continued to attack civilians with chemical weapons.