Tether says it helped freeze nearly $550 million in Iran-linked USDT during 2026, while Democratic investigators on a Senate subcommittee allege that delays in blacklisting some identified wallets let tens of millions of dollars keep moving.
A preliminary report released Sept. 28 by Democratic minority staff of the Senate Permanent Subcommittee on Investigations analyzed 846 crypto wallets that US or Israeli authorities had sanctioned or targeted for seizure over their associations with Iran and regional groups. The report said 84% transacted exclusively or nearly exclusively in USDT.
Sen. Richard Blumenthal, the Connecticut Democrat and ranking member of the subcommittee, referred the findings to the Treasury and Justice departments and asked them to investigate Tether's anti-money laundering and sanctions compliance.
The referrals do not establish that Tether violated federal law or that either department has opened a new case.
Tether published its own statement the same day, saying actions involving USDT had resulted in approximately $550 million being frozen across wallets that US authorities identified as connected to Iran's central bank and Iranian sanctions networks.
The money that moved before the freeze
The Senate report's 84% figure describes a selected population.
Investigators assembled the sample from wallets identified by the Treasury Department's Office of Foreign Assets Control and Israel's National Bureau for Counter Terror Financing as associated with Iran or regional groups. The dataset covered over five years of designations through August 2026.
For its analysis, the Senate report defined a wallet as transacting “predominantly” in a digital currency when that asset represented more than 80% of the dollar value of its aggregate transactions.
The number does not show what share of all USDT transactions is illicit, nor does it measure crypto's share of Iran's overall sanctions-evasion activity.
USDT is designed to track the US dollar and can move across blockchain networks without a conventional bank transfer. However, Tether retains issuer-level controls that can blacklist addresses and prevent USDT held at them from moving.
That makes the timing of a freeze the main issue for Democratic investigators.
The minority staff report examined 39 wallets identified by Israel's NBCTF in June 2023 as associated with Tawfiq Muhammad Sa'id al-Law, whom the US Treasury later sanctioned for providing financial services to Hezbollah.
According to the report, five of the addresses had been blacklisted, while the remaining 34 were not frozen until March 2024. Senate investigators calculated that more than $34.6 million in USDT moved out of those wallets after the Israeli seizure notice was published and before the remaining addresses were frozen.
Those findings by the Democratic minority are not a court determination that Tether violated US law. They also concern an earlier period than the enforcement actions Tether highlighted from 2026.
Tether points to action before public designation
On April 23, Tether said it supported US authorities in freezing more than $344 million in USDT across two addresses after receiving information from OFAC and other US law enforcement agencies.
The following day, OFAC updated the Central Bank of Iran's existing sanctions entry to add those same two blockchain addresses as digital-currency identifiers. The listing links the central bank to the IRGC-Qods Force and Hizballah.
Tether also said more than $130 million in USDT across four wallets was frozen in July as the Treasury expanded the Central Bank of Iran's listed blockchain addresses.
Those two disclosed actions account for at least $474 million of the approximately $550 million Tether says was frozen during 2026. The company did not provide a wallet-by-wallet breakdown reconciling the disclosed examples with the full headline total.
CEO Paolo Ardoino said Tether acts when authorities provide credible information and argued that public blockchains give investigators visibility into fund movements that cash does not.
Meanwhile, the Senate report said Tether acknowledged receiving a June 4 request for information and documents from the subcommittee but had not responded as of the report's publication.
Tether's Sept. 28 public statement did not directly address the report's 846-wallet analysis or the $34.6 million example of funds investigators say moved before addresses were frozen.
A separate US forfeiture case is seeking approximately $61 million in cryptocurrency allegedly tied to black-market Iranian oil sales. Federal prosecutors said the wider network moved more than $1.5 billion in proceeds and alleged that some funds were intended to benefit Iran's government and military, including the Islamic Revolutionary Guard Corps.
The Justice Department said the forfeiture action targeted cryptocurrency allegedly connected to sanctions evasion and money laundering tied to Iranian petroleum sales.
The two sets of evidence illustrate both sides of issuer-controlled stablecoins: authorities can immobilize large balances once they identify addresses, while delays before blacklisting can leave funds free to move.
Whether the delays identified by Senate minority staff represent isolated enforcement gaps or broader compliance failures is now the question Blumenthal has asked federal agencies to investigate.
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