TEHRAN -- Tough U.S. sanctions on Iran snapped back into effect today, targeting Iran's oil, shipping and financial industries. Secretary of State Mike Pompeo, speaking to "Face the Nation" on Sunday, described the measures as the "toughest ever" sanctions on Iran.

The reinstatement of the sanctions is the most tangible effect to date of the Trump administration's withdrawal from the 2015 nuclear deal with the Islamic Republic. In addition to hundreds of Obama-era sanctions being reinstated, the measures kicking in on Monday also expand the range of targets for US punishment.

Iran's normally moderate President Hassan Rouhani told a group of state employees on Sunday that it was time to Iran is facing a "war situation" under the new and renewed U.S. sanctions, but as CBS News correspondent Elizabeth Palmer reported from Tehran on Monday, he is also vowing that Iran will continue to sell its oil abroad.

Iranian officials say they will be able to run the country even if oil exports drop by more than half their 2017 peak, to a million barrels a day.

Rouhani also vowed that Iran would break the sanctions. Analysts say if it cannot sell enough oil using conventional means, it may resort to large-scale smuggling overland.

State television RTV led its morning news broadcasts with pictures of military exercises including anti-aircraft maneuvers. The exercises are annual affairs, but the airing of the pictures was a clear message of defiance to the U.S. and its allies.

The bravado was echoed at an anti-U.S. rally on Sunday outside the former US Embassy in Tehran. The head of Iran's powerful Revolutionary Guard warned America that it would threaten Iran at its own peril.

"I think, sorry to say… your president is a megalomaniac," proclaimed one demonstrator.



But on the fringes of the crowd, chants of "Death to America" were lackluster, and the protesters appeared simply to be going through the motions.

The weak economy and currency have already bruised ordinary people.

Few Iranians believe their government has the skill, or the political will, to get them out of this mess.

On Monday morning the Iranian currency held largely stable, but everyone recognizes that it's going to take some time for the punitive sanctions to really bite.