US President Donald Trump has said he could impose additional tariffs on countries that continue to trade with Iran, in an executive order signed on Friday.

The order does not specify the rate that could be imposed, but uses 25% as an example, and says it will apply to goods imported into the US from any nation that directly or indirectly purchases, imports, or otherwise acquires any goods or services from Iran.

Trump has not directly commented on the order but reiterated no nuclear weapons for Iran when speaking from Air Force One on Friday night.

This comes amid ongoing talks between senior US and Iranian officials in Oman, following several weeks of threats from both sides.

Trump threatened a 25% tariff on countries doing business with Iran earlier this year, in a post to Truth Social. In his earlier statements, he mentioned that effective immediately, any country doing business with the Islamic Republic of Iran will pay a tariff of 25% on any and all business being conducted with the United States.

At the time, no further detail was provided on how the tariffs would work in practice.

The White House states that this latest executive order reaffirms the ongoing national emergency with respect to Iran, indicating that the president can modify it as circumstances change. It positions the US as holding Iran accountable for its nuclear capabilities, terrorism support, and actions that threaten American security.

No immediate response from Iran has been given.

These sanctions coincide with the first US-Iran talks since the US bombed Iran's nuclear facilities last June, suggesting a desire for diplomatic resolution before more severe penalties might be enacted.

As negotiations unfold, the potential for escalated tariffs amplifies the urgency for a diplomatic resolution regarding Iran's nuclear ambitions and regional activities.