Trump ‘immediately’ imposes 25% tariffs on countries that do business with Iran. That could include China

(CNN) — President Donald Trump said on Monday that countries that do business with Iran will face a new 25% tariff. The announcement appears to mean goods from China, a major trading partner of both Iran and the United States, would become significantly more expensive to import.

“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 on Monday. “This Order is final and conclusive,” he added.

The White House declined to share additional information on the tariff and how the Trump administration plans to implement it, referring CNN to the president’s post.

Trump did not define what qualifies as “doing business” with Iran. The post raised a number of questions, including how these additional tariffs could work, which countries would be targeted and whether services and not just goods would face higher duties.

Trump’s announcement comes as he has floated US military intervention to “rescue” anti-government protesters in Iran, hundreds of whom have been killed. An ongoing communications shutdown, imposed by authorities on Thursday, has mostly isolated people in the country from the outside world.

The new tariff could mean a minimum 45% tariff rate on goods from China versus the current rate of 20%. In the first 11 months of 2025, China exported $6.2 billion worth of goods to Iran and imported $2.85 billion, according to Chinese customs data.

That’s before accounting for oil purchases, which China doesn’t publicly disclose. Analysts estimate that China has accounted for more than 90% of Iran’s oil trade in recent years, imported through intermediaries.

A trade war between the United States and China last year rocked global markets, with Trump raising tariffs on Chinese goods to a peak of 145% last year. The current tariff rate came about after lengthy negotiations.

In addition to China, India, the United Arab Emirates, and Turkey are considered major trading partners with Iran.

Trump doubled duties on goods from India this summer to a minimum 50% tariff, seeking to punish the country for buying Russian oil. He threatened to impose similar tariffs on other countries that purchase Russian oil, including China, its largest customer.

Throughout Trump’s second term, he has relied on a law known as the International Emergency Economic Powers Act to push import tax rates. His novel use of the law, however, is being challenged in the Supreme Court, with a verdict expected this month.

If the justices find Trump lacked the legal authority to impose such tariffs, not only will he lose his ability to adjust countries’ levies without virtually any restrictions, but US could be on the hook to refund at least $130 billion in tariff revenue.

This story has been updated with additional context.

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CNN’s Simone McCarthy contributed reporting.