Trump threatens secondary tariffs on Iran trade as pressure campaign escalates

US President Donald Trump has warned that any country doing business with Iran will be hit with a sweeping 25 percent tariff on all trade with the United States, dramatically escalating Washington’s economic pressure on Tehran as unrest grips the country.

Trump announced the move in a brief post on Monday, calling the decision “final and conclusive” while offering no guidance on implementation, exemptions or enforcement.

“Effective immediately, any Country doing business with the Islamic Republic of Iran will pay a Tariff of 25% on any and all business being done with the United States of America,” Trump wrote on Truth Social.

The declaration effectively revives and expands the logic of so-called secondary sanctions, threatening to punish third countries for maintaining commercial ties with Iran. It remains unclear which states would be targeted, but major economies including Russia, China, Brazil and Turkiye all maintain trade relations with Tehran. Iraq and the United Arab Emirates are also among Iran’s key trading partners, according to Trading Economics data.

The tariff threat lands amid one of the most volatile periods in US-Iran relations in years. Trump has repeatedly signalled a willingness to combine economic coercion with military force, warning Tehran to curb its nuclear and military programmes or face further strikes.

“Now, I hear that Iran is trying to build up again, and if they are, we’re going to have to knock them down,” Trump told reporters in December. “We’ll knock them down. We’ll knock the hell out of them. But, hopefully, that’s not happening.”

In June, the US bombed three Iranian nuclear facilities during a 12-day war initiated by Israel. Legal experts have said the US strikes likely violated international law, adding to concerns about Washington’s expanding use of force beyond UN frameworks.

Despite the aggressive rhetoric, the White House has tried to keep a diplomatic door ajar.

“Air strikes would be one of the many, many options that are on the table,” press secretary Karoline Leavitt said on Monday, while insisting Trump remains interested in diplomacy “if possible”.

Trump has also explicitly linked Iran’s internal unrest to US military threats. As antigovernment protests spread across the country, he warned that violence against demonstrators could trigger US intervention.

“If Iran shots [sic] and violently kills peaceful protesters, which is their custom, the United States of America will come to their rescue. We are locked and loaded and ready to go,” Trump wrote on January 2.

That threat came just one day before the US launched a military operation in Venezuela that led to the abduction of President Nicolas Maduro and his wife, reinforcing fears that Trump is increasingly willing to use force to advance political and strategic aims.

Human rights groups say hundreds of people may have been killed in Iran during the crackdown, though a nationwide internet blackout has severely restricted independent verification.