The United States imposed a new round of sanctions on Friday targeting a key financial facilitator for Iran’s new supreme leader, Mojtaba Khamenei, and a network of exchange houses and front companies, the Treasury Department announced. The measures, which blacklist 14 individuals and entities, were triggered by Tehran’s resumption of attacks on commercial oil tankers in the Strait of Hormuz earlier in the week, according to US officials.

At the centre of the action is Ali Ansari, an Iranian banker based in Dubai, whom the Treasury accuses of institutionalising large-scale embezzlement to build an overseas property empire for the benefit of Khamenei, his family, and the Islamic Revolutionary Guard Corps (IRGC). The Treasury alleges that Ansari, a former director of the now-defunct Ayandeh Bank, used shell companies and accounts across multiple jurisdictions, including a holding company in Saint Kitts and Nevis, to accumulate real estate and commercial holdings in Europe and the Gulf. The sanctions also target three Iranian exchange houses that the US says moved billions of dollars annually for sanctioned Iranian banks, as well as front companies in Hong Kong and the United Arab Emirates that obscured the transactions.

Viewed from Washington, the sanctions signal a shift in strategy. Treasury Secretary Scott Bessent stated that the department would “continue using every tool at its disposal” to isolate Khamenei and other elites from the global financial system, adding that the supreme leader was “hiding in seclusion while his regime crumbles.” President Donald Trump declared that the ceasefire agreed with Iran last month was over, though he said talks would continue at Tehran’s request. Iran’s top negotiator, Mohammad Baqer Qalibaf, responded on Telegram that the war would “never end with Tehran’s surrender,” and the government said it was ready for “all-out defence” if the US violated the memorandum of understanding. Brett Erickson, managing principal at Obsidian Risk Advisors, told Reuters that the new measures showed Washington was “no longer trying to salvage the existing framework, it’s preparing to replace it entirely.”

The sanctions follow a week of sharp military escalation. Three Qatari and Saudi commercial tankers came under Iranian fire, prompting days of US strikes on Iranian targets and Iranian retaliatory strikes on American military sites in Gulf states. The memorandum of understanding, which had outlined a gradual easing of sanctions, a ceasefire, and the reopening of the Strait of Hormuz, has effectively collapsed. The US had already revoked a waiver that allowed Iran to sell oil without sanctions. The Treasury warned that foreign financial institutions risk secondary sanctions if they facilitate transactions for the blacklisted entities. Diplomatic channels remain open, but the path to a durable agreement is now uncertain.