It mandates Russia to convert cash from oil sales into foreign currency by selling rubles when global oil prices are above a benchmark level of around $44 a barrel.
Analysts had previously expected that the Central Bank would not intervene until the ruble fell through the symbolic 80-mark against the dollar.
— started partial evacuations of their embassies in Kyiv, the Ukrainian capital, while more Western countries advised people not to travel to Ukraine or Russia.
The Russian stock market plunged 10% at one point Monday.