In what Donald Trump has called "economic D-Day," the US says the new economic sanctions will be "the single greatest financial offensive ever marshaled." Tehran says any support of the measures is an "act of war."

Treasury Secretary Scott Bessent on Monday is expected to announce the new measures after the U.S. vowed to impose an “unprecedented” level of economic warfare and isolation.

Bessent told CNBC that the sanctions will be the "toughest" in history.