US President Donald Trump proclaimed that all purchases of Iranian oil or petrochemical products must cease, emphasizing that any country or individual continuing to buy such products from Iran would face immediate secondary sanctions.

"They will not be allowed to do business with the United States of America in any way, shape, or form," Trump wrote on his social media platform Truth Social on Thursday, following the postponement of the latest round of Iran-US talks, which was due on Saturday.

A senior Iranian official informed Reuters that a new date would be determined based on the actions and stance taken by the US government.

According to Reuters, analysts have pointed out that for the US to effectively curb Iran's oil exports, it would need to enforce secondary sanctions against entities like Chinese banks, which play a key role in facilitating transactions for Iranian oil purchases, especially since China remains the biggest importer of Iranian crude.

Trump revisits 'maximum pressure'

This action is part of US President Donald Trump's renewed "maximum pressure" campaign on Iran, reinstated in February 2025, aiming to deny Iran all paths to a nuclear weapon, despite Iran's denying it ever intended to do so.

Last week, the US Treasury imposed sanctions on Iranian liquefied petroleum gas magnate Seyed Asadoollah Emamjomeh and his corporate network. It claimed in a statement that the network was "collectively responsible for shipping hundreds of millions of dollars’ worth of Iranian LPG and crude oil to foreign markets."

Concurrently, the US and Iran have engaged in indirect nuclear talks, with the fourth round originally scheduled in Rome on May 3, 2025, but now postponed. 

Trump, who withdrew from the 2015 nuclear deal in his first term, had threatened military action if no new deal was reached, though earlier this month, Trump stressed that diplomacy remains his preferred path and reportedly discouraged an Israeli strike on Iran.