And if China, the country that has so far been least committed to sanctions, joins, it could cut gasoline exports, which make up 40 percent of Iran's imports. The country is rich in natural gas but does not have modern gasoline refinement capacity.
But experts say even such stringent sanctions are unlikely to prevent Iran from provoking the world and to cause it to abandon its dream of a nuclear bomb.
"This regime and the Islamic Revolutionary Guard ... which runs the country, are very bloody minded and they would look at this as a challenge they are ready to meet," Baer said. "They will retaliate. ... They have a deterrence doctrine, which is looking at Saudi Arabia and the rest of the Gulf."
The Revolutionary Guard eventually wants its own nuclear bomb, and if it has it, it would be in the hands of the hardliners, "which makes it much more dangerous," Baer said.
At the G-20 summit Friday, Obama condemned Iran for not reporting its Qom facility to the International Atomic Energy Association.
"The Islamic Republic of Iran has been building a covert uranium enrichment facility near Qom for several years," the president said, alongside Great Britain's Prime Minister Gordon Brown and French President Nicholas Sarkozy.
Iranian President Mahmoud Ahmadinejad, speaking on CNN's "Larry King Live," denied the project had anything to do with nuclear weapons.
"How can he possibly accuse us of secretly engaging in an activity that did not take place?" Ahmadinejad said.
The discovery last week prompted representatives from the United States, Russia, China, Great Britain, France and Germany to call a meeting in Geneva with Iranian officials Thursday to demand immediate access for international nuclear inspectors to visit the Qom facility.
"Words are not enough," Secretary of State Hillary Clinton said on CBS's "Face the Nation."
"They're going to have to come and demonstrate clearly to the international community what they're up to."
Baer said Iran is likely to resist letting in International Atomic Energy Agency inspectors and would consider it humiliating. "I just don't think they're going to sit down for this," he told "GMA."
U.S. officials said they have known about the secret facility for a while.
"We have been following this for several years in cooperation with some of our international partners, watching and assessing what the Iranians were doing," Clinton said. "And, then, when this became known, actually through the Iranians beginning to provide some information about it, we disclosed the fact and gave the information we had to the International Atomic Energy Agency."
She said that if Iran really intended the facility to be used for peaceful purposes, not weapons production, it would have been disclosed earlier.
"So I guess one has to ask, if it's for a peaceful purposes, why was it not public? Why was the fact of it not generally known instead of through our working with partners to discover it?" Clinton said.
Defense Secretary Robert Gates said on ABC News' "This Week With George Stephanopoulos," "This is part of a pattern of deception and lies on the part of the Iranians from the very beginning, with respect to their nuclear program."
Gates would not say whether the United States is aware of other secret nuclear facilities in Iran. "I'm not going to get into that," he said. "I would just say that we're watching very closely."