US threatens Iran’s trade partners as Treasury prepares toughest-ever sanctions

The US has warned countries, banks and businesses supporting trade with Iran that they could face a new wave of economic penalties, as Treasury prepares what secretary Scott Bessent has described as the toughest sanctions Washington has imposed on Tehran.

Bessent said on Thursday that details would be announced on Monday, meaning the latest measures have not yet been formally specified or imposed. That distinction is important for banks and traders assessing their immediate compliance obligations.

The warning follows President Donald Trump’s threat of economic consequences against any country providing a financial or commercial lifeline to Iran.

Bessent indicated that Washington’s focus would include money transfers, purchases of Iranian oil and seaborne trade, while calling on US allies and other governments to choose whether to continue doing business with Tehran.

For trade and commodity financiers, the potential significance lies in the reach beyond Iranian entities themselves.

Secondary sanctions can create risk for non-US banks, shipping companies, commodity traders and other intermediaries if they transact with targeted parties or facilitate prohibited flows. But until Treasury publishes the new measures, it is not possible to state which jurisdictions, financial institutions, vessels, commodities or payment channels will actually be covered.

Markets have already reacted to the escalation. Brent crude settled at US$93.78 a barrel on Thursday, up 2.4%, while US West Texas Intermediate gained 2.3% to US$87.83. Both reached their highest closing levels since 24 July.

Oil remained above US$93 a barrel on Friday morning and was heading for a second consecutive weekly gain as traders assessed the implications of tighter pressure on Iranian exports and wider Middle East supply disruption.

Iran, meanwhile, has indicated that it will seek ways to reduce the effect of sanctions. Parliament speaker Mohammed Baqer Qalibaf called on Friday for stronger economic ties with Iraq and greater use of national currencies in bilateral trade.

The new US threat is therefore not yet a compliance rulebook. Its importance for trade finance lies in the prospect that the next round of measures will target the financial and commercial infrastructure used by third countries to keep Iranian trade moving.