President Obama on Thursday called on Syrian President Bashar Assad to leave office, ratcheting up pressure on the regime to end its violent suppression of demonstrators demanding a new democratic government.
The White House also announced that Obama signed an executive order intended to further isolate Assad. The new sanctions bar Americans from making new investments in Syria and ban importation of Syrian oil.
"The future of Syria must be determined by its people, but President Bashar al-Assad is standing in their way," Obama said in a prepared statement. "His calls for dialogue and reform have rung hollow while he is imprisoning, torturing, and slaughtering his own people.
"We have consistently said that President Assad must lead a democratic transition or get out of the way," Obama added. "He has not led. For the sake of the Syrian people, the time has come for President Assad to step aside."
In a joint statement, the leaders of Britain, France and Germany echoed Obama's demand that Assad resign.
"Our three countries believe that President Assad, who is resorting to brutal military force against his own people and who is responsible for the situation, has lost all legitimacy and can no longer claim to lead the country. We call on him to face the reality of the complete rejection of his regime by the Syrian people and to step aside in the best interests of Syria and the unity of its people," said the statement, which was signed by British Prime Minister David Cameron, French President Nicolas Sarkozy and German Chancellor Angela Merkel.
The three leaders said they were pursuing stronger sanctions by the European Union against Damascus.
In recent months, Obama has made clear his disapproval of Assad, while stopping short of explicitly calling on the Syrian leader to step down. The White House has instead insisted that Assad refrain from violence and help lead a transition to a more humane government. But violent crackdowns in Syrian cities made clear such an outcome was unlikely.
Privately, Obama administration officials voiced concern that they might not be able to back up the call for Assad to step aside — one reason for the delay in demanding Assad's resignation.
In his statement, Obama suggested that it might take time for Syria to usher in a more democratic government. In the end, he said, it will be up to the Syrians "to determine their own destiny."
He added that "we will continue to stand firmly on their side."
The White House hopes the new sanctions will force the issue. In a news release, the administration called the sanctions "the strongest financial action we have taken against the Syrian regime thus far."
Obama's action was greeted with a rare measure of bipartisan approval in Washington.
House Majority Leader Eric Cantor (R-Va.) released a statement saying he welcomed Obama's announcement.
"Under the Assad regime, Syria has become a proxy for Iran, a supporter of terror and a threat to United States interests and our allies in the region," Cantor said.
Times staff writer Henry Chu in London contributed to this report.