Sen. Lindsey Graham, R-S.C., a prominent conservative voice on national security issues, has shifted gears and now says there may be reason for optimism in assessing the U.S. withdrawal from northern Syria.

After talking with President Donald Trump last weekend, Graham said, "I am increasingly optimistic that we can have some historic solutions in Syria that have eluded us for years if we play our cards right."

Graham's conversation with Trump provided considerable insight into the president's thinking. Trump apparently is ready to use U.S. air power to protect a demilitarized zone occupied by international forces. Graham told Fox News this air power could help make sure Islamic State fighters do not "break out" and achieve military gains.

Graham, who had been strongly critical of the U.S. pullout last week, said the United States and local Kurdish allies could jointly establish a system to modernize Syrian oil fields and the revenue could go to the Kurds. "President Trump is thinking outside the box," Graham said.