The Russian rouble has plunged to its lowest level against the dollar since the immediate aftermath of the full-scale invasion of Ukraine in March 2022. The ruble hit 113 against the US dollar on Thursday. On Wednesday, Russia's central bank announced it would stop foreign-currency purchases to try and strengthen the currency and ease pressures on financial markets. The ruble has been sliding since late summer, falling by more than a third since August. Oil prices have fallen in the same period, hitting Russia's earning capacity from its most important commodity. That has piled pressure onto a war economy already...