US President Donald Trump says countries doing business with Iran will face a 25 percent tariff on trade with the US, in response to a deadly crackdown on anti-government protests in the Islamic Republic.
It's a big swing from the US president, but one that comes with little detail.
China, Iran's largest trading partner, says it "will take all necessary measures to safeguard its legitimate rights and interests," BBC reports.
Meanwhile, Trump's national security team is expected to meet later to discuss intervention options - the US president has already been briefed on a range of military and covert tools his country could use, officials tell the BBC's US partner CBS.
Human rights groups report hundreds have been killed by Iranian security forces at anti-government protests in recent weeks. One eyewitness tells the BBC "they fired directly into lines of protesters, and people fell where they stood".
Iran state media reports protests calmed last night, but the BBC has received footage from people who claim they continued in a number of different places - but a days-long internet blackout is making it difficult to verify information.
Protests in Iran began over two weeks ago, on 28 December, when shopkeepers took to the streets of the capital Tehran over another sharp fall in the value of the Iranian currency, the rial, against the US dollar on the open market.
The rial has sunk to a record low over the past year and inflation has soared - meaning every day items like cooking oil and meat have risen to crippling highs.
bd-pratidin/GR
