Russia could easily do what ed do here. Print money.
They could, but they might as well declare Russian tree leaves as their national currency, and save the paper and ink.
Since the Russian ruble isn't the world's primary reserve currency, the demand for Russian rubles is pretty much limited to Russians (who have no choice in the matter) and so it would become completely worthless. (With a value a bit over a US penny, the ruble is close to worthless to begin with.)