Tether announced it had frozen nearly $550 million in USDT tied to Iran during 2026, while a Senate subcommittee report alleged that delays in blacklisting certain wallets allowed tens of millions of dollars to move before they were restrained. The Senate Permanent Subcommittee on Investigations examined 846 crypto wallets that US or Israeli authorities had designated as linked to Iran or regional groups. Of those, 84% conducted transactions almost exclusively in USDT. The analysis, released September 28, was compiled from wallets identified by the Treasury Department’s Office of Foreign Assets Control and Israel’s National Bureau for Counter Terror Financing. It covered designations made over more than five years through August 2026. The report defined a wallet as transacting predominantly in a digital currency when that asset accounted for over 80% of its dollar transaction volume. The findings do not indicate the proportion of all USDT activity that is illicit, nor do they measure crypto’s role in Iran’s broader sanctions evasion efforts. USDT is a stablecoin pegged to the US dollar and can be transferred across blockchain networks without traditional banking intermediaries. However, Tether, as the issuer, can blacklist addresses to restrict movement of funds held there. The timing of freezes emerged as a focal point for investigators. The Senate report identified 39 wallets flagged by Israel’s National Bureau for Counter Terror Financing in June 2023 as connected to Tawfiq Muhammad Sa'id al-Law, a figure later sanctioned by US Treasury for facilitating financial services to Hezbollah. Of those, five were blacklisted promptly, while the remaining 34 were not frozen until March 2024. According to the report, more than $34.6 million in USDT was transferred out of those 34 wallets after an Israeli seizure notice was issued and before they were ultimately restrained. The Democratic staff’s findings do not constitute a legal determination that Tether violated federal law, nor do they mark the beginning of a formal enforcement action. Instead, they highlight a gap in the enforcement timeline that predates the high-profile freezes Tether cited in April and July 2026. On April 23, Tether stated it had assisted US authorities in freezing over $344 million in USDT across two addresses following guidance from OFAC and other law enforcement agencies. The next day, OFAC added those blockchain addresses to the Central Bank of Iran’s sanctions listing, linking them to the IRGC-Qods Force and Hizballah. A subsequent action in July froze more than $130 million across four additional wallets as the Treasury expanded its list of designated blockchain identifiers. Together, these two actions account for at least $474 million of the $550 million Tether reported as frozen during the year. The company did not provide a detailed reconciliation of these disclosed cases with the broader total. CEO Paolo Ardoino emphasized that Tether acts on credible intelligence from authorities and noted that public blockchains enable investigators to track fund flows that cash transactions typically obscure. In contrast, the Senate report underscored that delays in blacklisting certain addresses allowed significant volumes of USDT to circulate for months after being flagged. Whether these delays reflect isolated oversights or systemic compliance weaknesses remains under review. Blumenthal has urged the Treasury and Justice Departments to examine Tether’s anti-money laundering and sanctions compliance practices, though no formal investigation has been confirmed. A separate civil forfeiture case is seeking approximately $61 million in cryptocurrency tied to illicit Iranian oil sales, with prosecutors alleging a network moved over $1.5 billion in proceeds, some of which may have supported Iran’s military. The dual narrative — Tether’s public enforcement actions and the Senate’s scrutiny of procedural delays — illustrates the complex operational dynamics of issuer-controlled stablecoins in sanctions enforcement. Authorities can immobilize large balances once addresses are identified, but the interval between designation and action can permit substantial transfers to occur. The situation underscores ongoing challenges in monitoring and constraining digital asset use in sanction evasion networks.