Russia’s currency plummets over fears of sanctions’ bite.

Russia's currency fell by more than 30 percent against the dollar on Monday after the United States and its allies targeted some Russian banks.

The fall of the ruble is likely to cause inflation in Russia to increase. Russia's central bank said over the weekend that it would support Russian financial institutions that had been hit with sanctions and that banks would be able to carry out transactions in rubles and foreign currency.

The central bank raised its key interest rate to 20 percent on Monday to try to control the damage from the sanctions. The bank said it would release $7 billion of bank reserves that had been set aside as a buffer for consumer and mortgage loans.

Russia's finance ministry said Monday that it would require companies to sell 80 percent of their foreign currency holdings.

Last week, the United States, Europe and other allies took steps to exclude some Russian banks from international transactions by removing them from the financial messaging system. The United States and several allies decided to prevent Russia's central bank from using its reserves to undermine the sanctions.

The ruble dropped to a record low of 120 per dollar early Monday, but recovered somewhat by the afternoon.

A crash of the currency would make Russians feel worse. The prices of imported goods would go up.

Russia's central bank tried to project calm over the weekend, saying that the banking system was stable and that it would continue to provide banks with cash. All bank cards would work and services would be normal.