Lebanese opposition leaders are demanding Syrian President Bashar al-Assad formally announce the full withdrawal of Syrian troops and intelligence agents from Lebanon. They also called for the resignation of Syrian-backed Lebanese security chiefs, as thousands of protesters continued their demonstrations in Beirut. Earlier Wednesday, President Bush said Syria must end is political domination of Beirut and withdraw its forces. Mr. al-Assad met with Qatar's leader and said he would pull troops out of Lebanon, but he refused to give a definite timetable. Meanwhile, U.S. Deputy Assistant Secretary of State David Satterfield warned that democratic reform in Lebanon could strengthen Hezbollah, which the United States has designated a terrorist organization. The group provides social services in Lebanon that the government does not. Mr. Satterfield says U.S. aid programs could reduce Hezbollah's appeal.