Last year, when Ukraine failed to pay $20 million it owed for gas, Russia threatened to cut off supply, leading to another fierce argument between the two countries. A year earlier, too, their disagreement over similar payments had resulted in supply to about 20 European nations being disrupted, or even completely cut off, as gas from Russia reaches them through Ukraine. Russia’s usual response to any disagreement over price is to cut off supply. Mongolia knows this to its cost, as it is 100 per cent dependent on Russia for its petrol supply. This dependence has been there ever since Mongolians began using petrol 92 years ago.