The U.S. added four crypto wallets linked to the Central Bank of Iran to its sanctions list after a ceasefire agreement between the two countries broke down and air and drone strikes resumed.

The four Tron-blockchain wallets had received more than $165 million in stablecoins, according to Chainalysis. Tether blocked $131 million in USDT held by the accounts, though some of the funds had moved before the freeze.

Sanctioning the wallets gives exchanges, custodians and compliance firms a clear set of addresses to screen for. Iran’s central bank has accumulated at least $507 million in USDT, according to Elliptic, using the token to support the rial.

The U.S. Treasury Department’s Office of Foreign Assets Control (OFAC) has said its…