The Treasury Department also announced sanctions this week against Chinese and Iraqi banks that "facilitated transactions worth millions of dollars" for Iranian banks already under sanctions.
The actions by the administration and Congress "work very well together," according to Mark Dubowitz, an expert on Iran sanctions with the Foundation for Defense of Democracies in Washington. By further restricting energy trade through Obama's executive order, "the legislation essentially kicks in by giving the president the authority to go after, really, any entity who is aiding and abetting Iran" through the purchase of its oil by working around existing sanctions Dubowitz said.
This week's actions come amid charges by Republican presidential candidate Mitt Romney that the administration is not doing enough to force Iran to change course on its disputed nuclear program.
In a conference call with reporters this week, Ben Rhodes, the deputy national security advisor for strategic communications, said he had not seen anything in regard to Romney's rhetoric on sanctions that differed much from the administration's approach.
"We have thrown the book at the Iranian government in terms of leaving no stone unturned in the sanctions regime," Rhodes said. "And we are determined and committed to preventing Iran from obtaining a nuclear weapon."
Still, those like Dubowitz who follow the sanctions closely say more action can be taken to affect the Iranian calculus in regard to the West's demands that it come clean on its nuclear ambitions.
Dubowitz said action could be taken against purchasers of natural gas from Iran, which has the world's second largest reserves of that commodity, and there could be a complete designation of Iran's central bank as a zone of proliferation concern. That move would bar every financial transaction with the bank, with the exception of humanitarian goods, thereby setting up a de-facto trade embargo of the country.
"On the sanctions dial from zero to 10," Dubowitz said, "we are at seven or seven and a half. We need to get to 10."
The legislation now heads to the White House for Obama's signature.