US Threatens 'Most Severe' Sanctions Against Iran

With diplomacy aimed at ending the war with Iran still at an impasse, Washington is seeking to increase pressure on Tehran through economic measures described as “unprecedented.” After US President Donald Trump threatened to sanction any country doing business with Iran last week, US Treasury Secretary Scott Bessent announced a new round of economic measures that would “collapse” Iran’s government and called on nations to join.

On August 22, Tehran threatened to retaliate against any country joining the United States in imposing economic sanctions against it.

What new measures is the US threatening against Iran?

The Trump administration has run a campaign of economic pressure against Iran called “Operation Economic Fury” since the war began in February. The US is currently enforcing a naval blockade of Iran’s ports to halt oil exports, while targeting companies, brokers, and oil tankers accused of helping Iran sell oil abroad. The US also maintains comprehensive sanctions on Iran’s oil, shipping, and financial sectors.

In a Truth Social post on August 20, Trump said he would carry out the “most crushing economic campaign” against Iran. He said Iran had “failed to seize” the chance for a deal and would face “economic war and isolation on an unprecedented scale.” He also threatened to sanction any country trading with Iran, writing: “Any country that allows its financial institutions, businesses, airports or government agencies to provide any form of supplies to Iran will face MASSIVE ECONOMIC CONSEQUENCES.”

A day later, Treasury Secretary Bessent told CNBC that the US would impose “the most severe sanctions in history” on Iran. He described it as a “double punch” of blockade and sanctions, and warned the international community: “You are either with us or against us.” Bessent also called the strategy “the largest coordinated economic isolation in the history of the world.”

How has Iran responded?

Iran condemned the new US sanctions, particularly actions against other nations, as a “complete erosion of sovereignty.” Foreign Ministry spokesman Esmaeil Baghaei said the US statement was an “extraterritorial assertion of sovereignty” against UN member states, adding the ultimate result would be “the complete erosion of sovereignty—the foundation of the UN-based international system.”

Foreign Minister Abbas Araghchi called the new measures “doomed to fail.” On X, he wrote: “We have seen this movie before. Same absurdity. Different bullies.”

Could Iran target countries that comply with the US?

On August 22, Tehran threatened to retaliate against any country joining the US in imposing sanctions. Mohsen Rezaei, secretary of Iran’s Supreme National Security Council, warned: “Any country that participates in imposing economic restrictions on us will be considered an enemy” and threatened “shocking” retaliation. He outlined a three-phase strategy: negotiating to ease tensions, otherwise attacking that country’s interests, and warned neighboring states that if they join Trump’s economic war, “not a drop of oil” would leave the Gulf region.

Iran has conducted attacks on US military sites, infrastructure, and civilian areas in the region since the war began. Energy facilities in Qatar, Kuwait, Saudi Arabia, Bahrain, and the UAE have also suffered damage, mostly from debris of Iranian or proxy attacks that were intercepted.

Hamidreza Azizi, an Iran researcher at the Clingendael Institute, said Tehran is trying to establish early deterrence by signaling that even preparations for an attack could trigger an Iranian response. He pointed to two elements in the new “offensive doctrine”: pre-emptive strikes and asymmetrical retaliation.

How are other countries reacting to Trump’s demands?

China has brushed off Trump’s threats. Foreign Ministry spokesman Lin Jian said: “Imposing sanctions and pressure does not help resolve the issue,” and called on parties to resolve through diplomatic and political means.

Gulf states, both Iran’s neighbors and US allies, are caught in the middle. Last week, the UAE imposed an indefinite trade embargo on Iran after accusing it of firing two ballistic missiles at the country, an allegation Tehran denies. However, analysts say many Gulf states fear chaos if Iran’s government collapses. Simon Mabon, a professor at Lancaster University, said: “Ultimately, Gulf states cannot change geography. They have to live and work with Iran.”

Can China and Russia shield Iran from US measures?

Despite US threats to sanction any country trading with Iran, analysts say Trump’s leverage over China and Russia, Iran’s major trade partners, is limited. Paul Musgrave, an associate professor at Georgetown University in Qatar, said Trump is trying to unilaterally impose coordinated sanctions that normally require multilateral cooperation, including China, Russia, and other permanent UN Security Council members.

Some sectors in Russia and China have minimal dependence on the US financial system, including most of China’s refineries. According to data firm Kpler, China bought 80% of Iran’s shipped oil in 2025. Analysts say China could retaliate if the US sanctions its major banks. Yu Jie, a senior research fellow at Chatham House, said: “Trump wants to stabilize relations with China, while Beijing wants a temporary ceasefire with Washington.”

Although Russia is a less significant trade partner than China for Iran, Moscow and Tehran have developed significant trade and military ties that bypass Western channels, notably Iran supplying Shahed drones to Russia during the war in Ukraine.