Today, for the fourth time since 2006, the United Nations Security Council voted for economic sanctions against Iran. The council's expressing its displeasure with Tehran's nuclear program. Some Iranian banks and companies tied to that program are going to face new restrictions. But the first three rounds of sanctions didn't do anything to convince Iran nuclear power's not in their self-interest. So what are the odds this one will?

By Brett Neely

Today's Security Council resolution expands an international arms embargo against Iran. More Iranian banks and companies involved with the nuclear weapons program will be added to a U.N. blacklist and won't be able to trade abroad.

"It makes it a little bit more difficult for Iran to do business as usual," said Jacqueline Shire, a former U.S. diplomat and a U.N. weapons inspector who's now at the Center for Science and International Security.

But today's new sanctions don't touch Iran's oil industry, its biggest source of revenue. That decision faced up to a political reality, says Shire.

"China wanted assurances that nothing in this resolution would really change the way Iran does its daily non-nuclear-related business," she said.

The sanctions are designed to increase the pressure on Iran, says George Lopez, who is a sanctions expert at the U.S. Institute of Peace.

"You know it's not a total lockdown, let's not fool ourselves here," Lopez said. "But it does have a ripple effect that changes that the way the leaders in Tehran will think about the costs of continuing to pursue this nuclear program."

But three earlier rounds of U.N. sanctions haven't stopped the Iranian nuclear weapons program. Karim Sadjadpour, an associate at the Carnegie Endowment, says Iran has plenty of oil to export and an economy that's already been isolated for decades.

"Further sanctioning Iran is kind of like sentencing a recluse to house arrest," Sadjadpour said.

Meanwhile, the European Union plans to introduce even tighter sanctions of its own as early as next week.