ANALYSIS: From Jill Dougherty, CNN Foreign Affairs Correspondent
At first glance, the economic sanctions announced Thursday by the Obama administration look draconian: freezing Syrian assets under U.S. jurisdiction, banning Americans from doing any business with Syria, banning U.S. imports of Syrian oil or petroleum products, identifying five Syrian state-owned companies that are most involved in Syria's petroleum sector.
A senior administration official who briefed reporters on the sanctions, speaking on background because of the diplomatic sensitivity of the issue, said the new sanctions "strike at a crucial stream of funding in hard currency for the regime," potentially damaging the regime's ability to carry out its bloody repressions.
At the State Department briefing Thursday, spokeswoman Victoria Nuland said, "The net effect of the sanctions that we have imposed today is to close the U.S. financial sector to Syria."
But to really hurt the regime of Bashar al-Assad, the Obama administration's allies will have to take similar steps.
After all, even though Syria gets approximately one-third of its income from its oil exports, that administration official confirmed that approximately 90% of Syria's oil exports go to the European Union, not to the United States.
"Action taken by the E.U. or by E.U. member states to cut off the import of Syrian oil will significantly enhance the pressure on the Syrian regime," the official noted.
That, certainly, is what the Obama administration is hoping, said Nuland: "I think our first priority is to see other countries around the world with companies operational in Syria take national measures. And I think our hope and our expectation is that in coming weeks and months, and weeks and days, more countries will take such action."
Thursday the Obama administration heard some encouraging words from E.U. High Representative Catherine Ashton, who said the E.U. is adding more names to the list of Syrians targeted by restrictive measures already in place and is "moving ahead with discussing further restrictive measures that will broaden its sanctions against the Syrian regime."
But sanctions can run into problems, said Joshua Landis, director of the Center for Middle East Studies and associate professor of Middle Eastern Studies at the University of Oklahoma.
"We've seen in places like Sudan where America has placed sanctions and China has come in and picked up the slack."
"China is desperately in need of energy," Landis told CNN, and it sees Western sanctions as an anti-China policy because the measures drive up oil prices.
Landis also questioned whether sanctions could end up hurting the Syrian people. He outlined a possible scenario in which subsidies are slashed to keep the Syrian poor fed. People will begin to starve, creating outflows of refugees, he said.
"The idea is that will undermine the regime and it will collapse," he said, but if it doesn't happen "we'll be on the slippery slope toward military intervention."
The Obama administration vowed to try to avoid hurting Syrian citizens.
"We will work to minimize the collateral effect of these sanctions on the average Syrian citizen," the senior administration official said. "But it is our firm belief that the international community must join the U.S. and act now to choke off the financial lifelines to the Syrian regime and its supporters."
"We look forward to the time when the resources of the Syrian government are used for the benefit of the Syrian people, not to brutalize them and to try to crush their legitimate aspirations."
CNN's Joe Sterling contributed to this report