The US has announced a host of sanctions against Iran and its supporters as part of what Treasury Secretary Scott Bessent said was “the single greatest financial offensive ever”.

Labelling it an “economic D-Day” for Iran, Bessent said the US would sever all economic ties with the country and added that any nation financially partnering with Iran would also be isolated.

“Our objective is to sever every economic lifeline that sustains this tyrannical regime until Tehran stands alone,” he told a press conference.

Iran has warned it would shut down all oil exports from the region if the war with the US and Israel continues.

The Iranian regime has also issued a new warning to shipping to not pass through the Strait of Hormuz without its permission, according to Reuters.

One fifth of the world’s oil and gas usually passes through strait, a narrow waterway south of Iran, but the flow has been effectively blocked by the country since the conflict began at the end of February, leading to higher oil prices globally.

At a press conference on Monday outlining what has been called “Operation Economic Outcast”, Bessent said the US was launching an “economic onslaught against Iran’s financial connections around the globe”.

“Iran now faces a very clear choice with only two paths before them: complete global isolation….or a path back to normalcy with an opportunity to rejoin the global economy,” he said.

The treasury secretary added America was “no longer managing the Iranian threat, we are ending it”.

Bessent said the Treasury Department had mapped networks, facilitators and financial channels used by Iran to evade sanctions to trade oil.

The department said it has issued determinations against five sectors: digital assets, technology, gold, aviation and shipping. The Treasury has also imposed sanctions on almost 60 entities, individuals and vessels.

However, the latest threat to the Iranian regime follows several U-turns and extended deadlines from US President Donald Trump’s administration in its efforts to end the conflict.

Over the course of the war, previous threats have included Trump saying in April that “a whole civilisation will die tonight” unless Iran agreed a deal to end the war and unblock the Strait of Hormuz.

The US eventually climbed down from that position after mediator Pakistan intervened and called for more diplomacy.

The economic impact of the Iran war is being felt in the US and across the world. Higher oil prices have fuelled concerns over the cost of living, with petrol and diesel prices much higher than they were a year ago.

In the US, gasoline prices have surpassed $4 a gallon and affordability is among the top concerns of American voters ahead of the mid-term elections in November.

On Monday, a barrel of Brent crude, the global benchmark for oil prices, was $93.

Last week, Bessent announced the US government would intervene in the bond markets and buy back more government debt in a bid to boost demand for bonds and lower borrowing rates.

But the impact of the announcenment was short-lived, with long-term borrowing costs bouncing back up a day later.