US President Donald Trump's administration is set to unveil sanctions against Iran, in what it is calling "the single greatest financial offensive ever marshalled against an adversary".
But Iran is already subject to one of the world's most extensive sanctions regimes, built up over decades and covering much of its economy.
The US has imposed punitive measures on Iran since 1979, aiming at the country's banking and financial systems, oil and petrochemical industries, shipping, aviation, military programmes, cryptocurrency networks and individuals and companies. US secondary sanctions also threaten foreign banks and companies that do business with sanctioned Iranian entities.
European and other sanctions
The sanctions extend well beyond Washington. The EU, UK, Canada and Australia maintain their own restrictions, while UN sanctions against Iran's nuclear and missile activities were reimposed in September 2025 through the Joint Comprehensive Plan of Action (JCPOA) snapback mechanism.
The UN measures include restrictions on arms transfers, sensitive nuclear materials and technology, ballistic-missile activity, asset freezes and other restrictions on designated individuals and entities.
The EU has imposed sanctions on Iran over its nuclear and missile programmes, military co-operation and the supply of drones and missiles to Russia. It has also introduced measures against Iranian officials, security forces and organisations over human rights abuses, repression of protesters, detention of European nationals and cyber-attacks.
The UK's sanctions are aimed at Iranian weapons proliferation and the decision-makers involved, alongside broader measures against officials, security forces and the Islamic Revolutionary Guard Corps (IRGC) over human rights abuses and the suppression of protesters.
Australia maintains sanctions on Iranian individuals and organisations, principally over human-rights brreaches and the violent suppression of protesters.
Canada has put restrictions on designated Iranian individuals and their property and imposed an arms embargo and measures affecting Iran's oil and gas sector, oil-refining equipment, investment and services connected with Iranian shipping.
Ukraine has measures in place mainly focused on Iran's military support for Russia. In February, it designated the IRGC a terrorist organisation, citing repression inside Iran and the supply of Shahed drones to Russia.
The Financial Action Task Force's (FATF) continued blacklisting of Iran is not a conventional sanctions regime, but it creates another major obstacle to international finance by requiring banks to apply enhanced scrutiny to transactions involving the country.
And last week, the UAE declared it had halted “all trade, commercial exchange and financial transactions with Iran” due to the threat the country poses to the region.
Evasion efforts
The cumulative effect is an economy that has spent decades adapting to international isolation. Iranian banks face severe restrictions on international finance, while oil exports remain subject to extensive sanctions. Shipping companies, insurers and traders connected to Iranian exports can face penalties.
Tehran has developed ways to bypass the restrictions, using front companies, exchange houses, offshore accounts, opaque ownership structures and alternative financial channels.
Its oil trade relies on complex shipping arrangements, including ship-to-ship transfers and vessels with opaque ownership. Cryptocurrency has also become part of the system.
China remains a major importer of Iranian crude, while foreign intermediaries provide channels for Iranian businesses to reach international markets despite formal restrictions.
US measures have increasingly focused on the infrastructure used to evade sanctions rather than simply adding more Iranian entities to blacklists.
Naval blockade
In July, the US Treasury imposed sanctions on more than 100 vessels linked to Iran's shadow fleet, describing it as a covert logistics network that allows Tehran to keep oil revenues flowing. Washington has also targeted exchange houses, clandestine currency networks and cryptocurrency channels used to move money outside the conventional banking system.
Other financial tools remain available. Section 311 of the US Patriot Act allows the Treasury secretary to designate a foreign financial institution or jurisdiction as a primary money-laundering concern, potentially restricting its access to the US financial system. Such measures could target foreign institutions that continue to facilitate Iranian trade.
The wider sanctions regime also gives Washington and its allies scope to tighten enforcement. The focus is increasingly on foreign banks and companies willing to keep dealing with Iran, shadow-banking networks, cryptocurrency and exchange-house channels, oil buyers and intermediaries, and the vessels used to move Iranian exports.
The US is now also attempting to constrain the physical movement of Iranian oil. Its naval blockade of Iranian ports and pressure on the Strait of Hormuz have gone beyond traditional sanctions.
For the Trump administration, the problem is that much of the conventional sanctions toolkit has already been used. After decades of restrictions, Iran has built an economy around surviving them.
