Newly uncovered trade documents reveal that Russia’s state-controlled Promsvyazbank secretly shipped about $2.5 billion in cash to Iran in 2018, keeping Tehran’s economy afloat just as U.S. sanctions under president Donald Trump took effect. The revelation exposes a major sanctions-busting alliance between Vladimir Putin and Iran’s leadership, underscoring Moscow’s deep financial and political backing for its embattled Middle Eastern ally. According to the data, 34 shipments—nearly five tonnes of banknotes— were sent over four months from Russia to Tehran via the Caspian route, starting on August 13, 2018, days after fresh U.S. penalties hit Iran.