President Donald Trump has said the US will inflict “TREMENDOUS Economic Consequences” on any country that helps or does business with Iran.

He wrote in all capital letters on Truth Social that he was launching “the most crushing economic operation ever taken against any country!” He gave no further details, and did not name any other nation.

It comes after a 60-day ceasefire with Iran expired on Monday, with no sign of a diplomatic or military off-ramp to the conflict that the US and Israel began at the end of February.

Trump’s latest move appears to extend the pressure campaign of Operation Economic Fury, launched in April to sanction foreign banks or firms that do business with Tehran.

In Wednesday evening’s social media post, Trump said he was launching “economic D-Day” on Iran because the Islamic Republic had failed to make a deal with the US.

“ANY country that allows its financial institutions, businesses, airports, or government entities to provide any type of lifeline to Iran will itself face TREMENDOUS Economic Consequences,” Trump said.

He did not specify what punishment countries might face.

Trump continued: “Oil smuggling, swap lines, cash transfers, exchange houses, ship registries, front companies – It all needs to stop NOW. You know who you are.”

It comes a day after United Arab Emirates, a US ally, announced it would be severing all financial and economic ties with Iran, following a new missile threat from the country.

The UAE’s defence ministry said it had detected two ballistic missiles launched from Iran targeting maritime traffic, both of which landed in the sea.

Iranian entities have long used Dubai’s financial system to transfer money through exchange houses and shell companies.

Following the UAE’s decision, Iran’s armed forces warned neighbouring Gulf countries against providing support to the US military, saying any assistance given to US forces would be considered collusion.

The president’s comments come nearly a week after Treasury Secretary Scott Bessent said the US would impose economic isolation on Iran “like the world has never seen before”.

The BBC has asked the White House and US treasury department for comment.

Earlier this week, Trump also reportedly threatened to bomb Oman – a US ally – if it “gets in the way” of his administration’s own talks with Iran, during a phone interview with a Fox News reporter.

The US and Oman have been negotiating separately with Tehran to reopen the Strait of Hormuz, a waterway that is vital to the global economy.

The conflict has significantly disrupted traffic through the key Strait of Hormuz shipping route, pushing up global energy prices.

Around 20% of the world’s crude oil and liquified natural gas (LNG) usually passes through the strait.

Ahead of the US midterm elections in November, Trump faces pressure over how much the war is costing American consumers.