The Treasury Department wants US banks and other financial institutions to monitor for suspected Iranian money-laundering networks that use their funds to smuggle sanctioned oil through shell companies and cryptocurrency networks.

The move, which effectively deputises the global financial system to help disrupt Iran’s sanctions-evasion infrastructure, comes as the US and Iran reached another impasse over how to end their war while their ceasefire has grown increasingly shaky.

US President Donald Trump on Monday said the Iran ceasefire is on “life support” after he rejected Tehran’s latest proposal to end the war.

The Trump administration is calling on banks to flag certain customers who may launder funds for Iran’s Revolutionary Guard - including newly formed companies moving unusually large amounts of money, firms that route payments through multiple intermediaries or transactions connected to Iranian cryptocurrency firms, among other indicators.

As part of the US initiative to monitor Iranian oil sales, banks are being asked to watch out for oil labelled as “Malaysian blend” to disguise its Iranian origin, missing or falsified shipping documents or ship-to-ship oil transfers that obscure where cargo came from.

A Treasury Financial Crimes Enforcement Network report released on Monday says oil firms linked to Iran conducted roughly US$4 billion in transactions in 2024.