Bithumb said it would begin restricting all cryptocurrency deposits and withdrawals involving Shelbit, Aban Tether and Crypto Home DMCC, tightening compliance after the U.S. Treasury sanctioned the firms over alleged support for terrorist groups including Iran's Islamic Revolutionary Guard Corps and over laundering illicit proceeds. The move follows OFAC's action against Shelbit, Aban Tether and network operator Siavash Kayvanpour, whom Treasury accused of moving cryptocurrency tied to the IRGC as Washington broadens pressure on Tehran's financial networks. OFAC said IRGC-linked wallets sent more than $1 million to Shelbit and received more than $2 million back, while wallets linked to Kayvanpour sent more than $2 million to Nobitex, Iran's largest crypto exchange, which the United States blocked in June. Treasury said Kayvanpour ran Shelbit from Georgia and built front companies in Poland and the UAE, alleged the exchange laundered tens of millions of dollars for a Persian-language gambling network, and said Aban Tether processed millions with previously sanctioned Iranian exchanges. New blockchain analysis from TRM Labs suggests Shelbit operated less like a typical exchange than a high-volume settlement network, tracing more than $6.3 billion through Shelbit-linked wallets between May 2024 and March 2026, with flows heavily concentrated in Tron-based USDT and little residual balance left in wallets. TRM also identified links between Shelbit and Russia's A7 payment network, Grinex and other Russian and Central Asian services, indicating the infrastructure was used across multiple sanctions-constrained payment corridors rather than for a single client base.