Senate investigation finds rampant use of Tether’s stablecoin by Iranian regime

The US Senate Permanent Subcommittee on Investigations has turned its spotlight on the world’s largest stablecoin issuer, finding that the Iranian regime widely used Tether’s USDT token to evade international sanctions. The inquiry, led by Sen. Richard Blumenthal, lays out a trail of hundreds of millions of dollars in USDT flowing through wallets connected to Iranian oil transactions, the country’s central bank, and entities aligned with Iran’s Revolutionary Guard Corps.

Iran’s Central Bank has reportedly accumulated at least $507 million in USDT to keep its economy functioning under heavy financial restrictions.

The paper trail and the crackdown

The investigation draws on blockchain analysis and reporting from The Wall Street Journal and Fortune, which documented USDT transfers tied to illegal Iranian oil sales and support for IRGC-linked groups. On June 4, 2026, Blumenthal sent a formal records demand to Tether seeking documentation about USDT’s role in Iranian and Russian shadow banking networks.

That demand came just two days after the Office of Foreign Assets Control sanctioned four Iranian cryptocurrency exchanges: Nobitex, Wallex, Bitpin, and Ramzinex. OFAC cited ties between those platforms and IRGC money laundering operations, effectively cutting them off from the legitimate financial system.

On September 14, 2026, the Department of Justice filed a civil forfeiture complaint in New York seeking to seize approximately $61.2 million in USDT from wallets that processed illicit proceeds from Iranian black-market oil sales. The complaint alleges those funds directly benefited the Iranian government.

All of this falls under an umbrella operation the government has dubbed “Operation Economic Fury.” Since April 2026, nearly $1 billion in Iran-linked digital assets have been sanctioned or frozen under the initiative.

Tether’s response: cooperation or damage control?

Tether froze over $344 million in USDT in April 2026 tied to wallets linked to Iran’s Central Bank. It followed that up with an additional $131 million freeze in July 2026 targeting the same network.

Combined, those freezes represent roughly $475 million in sanctioned assets that Tether locked at the token level. The ability to freeze specific wallets is a feature baked into Tether’s smart contract. The gap between “we freeze assets when told to” and “we proactively prevent sanctions evasion” is the exact territory this Senate investigation is probing.