In announcing sanctions against Russian politicians and one bank Thursday, U.S. officials made clear that American financial institutions should prepare for more, and soon. Under one of two executive orders issued earlier this month, the United States told banks to freeze the assets of Bank Rossiya, a "crony bank" used by the Russian president and his close allies. The blacklisting of the bank came as part of a sanctions package targeting the head of the institution and 19 others, the majority of whom serve in Russia's executive and legislative branches of government. The designations coincided with the issuance of a...