The sweeping sanctions will see 700 people blacklisted, the US Treasury has announced. These include persons that were granted relief under the 2015 deal, as well as over 300 new names, Treasury Secretary Steven Mnuchin told reporters.
Sanctions will also target payments through the special mechanism that the EU has been creating specifically to avoid Washington's penalties and to keep buying Iranian oil.
Mnuchin has also threatened sanctions against the transaction service SWIFT.
"SWIFT is no different than any other entity," Mnuchin told reporters. "We have advised SWIFT that it must disconnect any Iranian financial institutions that we designate as soon as technologically feasible to avoid sanctions exposure."