US President Barack Obama called on Thursday for the Syrian president, Bashar al-Assad, to leave power, and issued a new executive order providing for additional sanctions. It is the first time the United States has explicitly called for Mr. Assads departure from power. For the sake of the Syrian people, the time has come for President Assad to step aside, Mr. Obama says in the statement issued by the White House. The actions come in response to the deadly crackdown Syrian forces have been waging against pro-democracy protesters across the country. Secretary of State Hillary Rodham Clinton was scheduled to speak at 10 a.m. Eastern time about the sanctions, which the official said would be much sterner than previous measures. We believe that this very tough action will lend additional force to the presidents words, an administration official said shortly before the statement was issued.