U.S. federal prosecutors are investigating whether Binance, the world's largest cryptocurrency exchange, failed to block certain Iran-linked transactions and potentially violated U.S. sanctions rules. Federal prosecutors in Manhattan are reviewing the exchange's sanctions controls, with the Justice Department's criminal division also involved. Authorities are examining whether Binance knowingly allowed the transactions, although the specific transactions under review and whether charges will follow remain unclear. Binance said it has a zero-tolerance policy for sanctions violations, is cooperating fully with law enforcement and continues to identify and block malicious actors. The investigation follows Binance's 2023 guilty plea over sanctions and anti-money-laundering violations and its agreement to pay a $4.3 billion fine. The company says it has since strengthened compliance, with more than 1,500 employees, about 25% of its workforce, assigned to compliance functions in February. Separately, Manhattan prosecutors are pursuing forfeiture of $61 million allegedly generated by Iranian black-market oil sales and laundered through Binance, without accusing Binance itself of wrongdoing in that case. A separate February report said more than $1 billion moved through Binance from entities linked to Iran, a finding the exchange partly disputed. Binance co-founder Changpeng Zhao pleaded guilty in the 2023 settlement, stepped down as chief executive officer, served four months in prison and was later pardoned by U.S. President Donald Trump last year.