The U.S. government has blocked roughly $344 million in cryptocurrency it believes is connected to Iran, stepping up financial pressure as diplomatic efforts remain uncertain, CNN reports.

Treasury officials said multiple digital wallets were targeted as part of a broader effort to cut off funding channels linked to Tehran.

Authorities cited blockchain analysis showing transactions connected to Iranian exchanges and accounts associated with the country’s central bank.

The freeze was carried out with assistance from Tether, which said it acted after receiving information from U.S. agencies about suspected illicit activity.

Experts say the move is significant but unlikely to materially alter Iran’s financial position, as the country has long adapted to sanctions and increasingly relies on cryptocurrency to bypass restrictions.