The White House said Assad's deadly crackdown on protesters had put Syria and the Middle East on a "very dangerous path," as Washington extended a raft of recent sanctions to include a businessman close to Assad and his family.
In toughening its stance, President Barack Obama's administration appeared to be moving toward a first direct call for Assad to go, a step it has so far resisted, following an escalation of violence in the revolt hub of Hama.
|File picture dated December 3, 2010 shows Syria's president Bashar al-Assad gesturing during a press conference after talks with Ukraine's President Viktor Yanukovych in Kiev.|
US Secretary of State Hillary Clinton said the United States would urge the Europeans, Arabs and others to do more to press Syria to stop its deadly crackdown on pro-democracy protesters.
The chief US diplomat also said Assad's regime was responsible for the deaths of over 2,000 people, repeating that Washington believes Assad has "lost his legitimacy to govern the Syrian people."
She voiced hope that the UN Security Council's statement on Wednesday condemning Assad's government would be the first of many future steps to make Damascus "pay the price" for its violent repression.
State Department deputy spokesman Mark Toner said Robert Ford, the ambassador who returned to Washington this week for consultations and his Senate confirmation, would head back to Damascus.
"It's very important for him to get back on the ground where he can go back to his vital work to outreach to the Syrian opposition, as well as to continue to press our concerns with the Syrian government," Toner told reporters.
Ford will convey the toughening attitude from Washington -- one reinforced by the UN statement condemning attacks on civilians and calling for those responsible to be held "accountable."
The ambassador, who infuriated the Syrians with a visit to Hama last month, told ABC News television that he intends to continue traveling around Syria even as he was "personally nervous about the fate" of people he met.
He said that while he would be careful to avoid endangering people, it was important to show solidarity with the Syrians.
White House spokesman Jay Carney meanwhile hardened US rhetoric.
"It has become very clear around the world that Assad's actions place Syria and the region on a very dangerous path," he said.
"Assad is on his way out... we all need to be thinking about the day after Assad as Syria's 23 million citizens already are.
"It is very safe to say that Syria will be a much better place without President Assad."
Carney has said that Washington has no interest in seeing Assad survive simply to preserve regional "stability," hardening its line on a "grotesque" crackdown on dissent.
Some analysts have speculated that Washington has been wary of directly calling for Assad to quit because of anxiety that sectarian chaos, civil war and a Middle East power vacuum might follow the demise of his regime.
Others say the US government has very limited leverage to impact the political situation in Syria, whether it calls for Assad's ouster or not.
The US Treasury Department froze the US assets of Mohammad Hamsho and his company, Hamsho International Group, and prohibited US entities from engaging in any business dealings with them.
The government said Hamsho was "one of Syria's top businessmen" with interests in multiple sectors and a "close business associate" of Assad's brother Maher, serving as a "frontman" for him and a number of his businesses.
Maher heads the army's elite Fourth Division, with observers saying he has spearheaded the crackdown on pro-democracy protesters.
Obama signed an executive order in May imposing targeted sanctions on Assad and several high-ranking Syrian government officials for their bloody repression of pro-democracy demonstrators.
But Republican White House hopeful Tim Pawlenty accused Obama of "inaction" -- and urged him instead to call on Assad to step down, recall the US ambassador and impose "additional economic sanctions."
The administration argues it can better use its influence with the Syrians with Ford in Damascus than outside the country.
US officials had said the Obama administration had considered sanctions against Syria's oil and gas sector, but did not say why it discounted such a move.
There has been a bipartisan move in the Senate to impose sanctions against the oil and gas sector, with oil reportedly accounting for about a third of Syria's export earnings