Secretary of State Rex Tillerson predicts Syrian President Bashar al-Assad won't be in office much longer.  But he told reporters in Italy, where he attended a meeting of foreign ministers, that the U.S. is not "presupposing" how Assad will leave.   Tillerson is now in Moscow for meetings with Russian officials amid rising tensions between the two countries. Russia is an Assad ally and has said that last week's U.S. airstrike in Syria has damaged relations between Moscow and Washington.