Western media report that the FBI is investigating recent attacks by Russian hackers on the U.S financial system that are seen as possible retaliation for U.S. government sanctions against Russia.
The reports quote sources who say Russian hackers targeted JPMorgan Chase and at least one other U.S. bank.
Bloomberg.com reports that the attack led to the loss of sensitive data.
The financial news service cited security experts who said the attack appeared "far beyond the capability of ordinary criminal hackers."
The New York Times reported that JP Morgan Chase and at least four other firms have been hit during August by what it described as "coordinated attacks" that siphoned off huge amounts of data, including information on checking and savings accounts.