Consider the following analogy. The equilibrium price of a car is $10,000. If the government imposes no restrictions on car prices (i.e. car prices are flexible), then the free market price of a car will be $10,000. Further, there will be no surplus or shortage of cars -- everyone who wants to buy a car (at $10,000) will find one to buy, and everyone who wants to sell a car (at $10,000) will find a customer. Now, suppose the government imposes a price floor on cars of $15,000. At the official price of $15,000, many people will want to sell cars, but few people will want to buy cars – there will be a surplus of cars. If the government wants to avoid ending up hip-deep in unsold cars, it will have to buy the extras itself. (Note: this is precisely what the government does in the case of farm subsidies.)
In the case of a fixed exchange rate, the Russian government declares that the official price of 100 rubles is $1. Suppose, however, that the equilibrium price of 100 rubles is $0.75. That is, people would be willing to trade 100 rubles for $1, but the government only allows trades of 100 rubles for $0.75. At the official price of 100 rubles to $0.75, many people will want to sell rubles (sellers receive $0.25 more than the equilibrium price), but few will want to buy rubles (buyers must pay $0.25 more than the equilibrium price). The result is that there will be a surplus of rubles: there are more people willing to sell than there are people willing to buy. As in the car example, if the government wants the market to continue, it must take up the slack. In this case, the Russian government must buy the surplus rubles (at the official price of 100 rubles to $1). How does the Russian government buy rubles? It pays for the rubles on the market with, for example, US dollars.
So now everything is fine. The official exchange rate is 100 rubles to $1. The Russian government buys up the surplus rubles that the market does not want, and life goes on.
Not so fast. The Russian government is buying these surplus rubles with US dollars. The US dollars are coming out of a stockpile that the Russian central bank has built up. What happens when the Russian central bank starts to run out of dollars? When the Russian central bank starts to run out of dollars, it becomes harder for it to buy up the surplus rubles. If the central bank loses the ability to buy up surplus rubles, then it becomes powerless to enforce its fixed exchange rate. The Russian government now has three options: (1) revert to a flexible exchange rate (which would cause the price of rubles to immediately fall to 100 rubles to $0.75), or (2) suspend trading in rubles (which is what the government did first), or (3) devalue the ruble so that the fixed exchange rate is closer to the equilibrium exchange rate (which is what the government did next). Note that option 3 does not solve the problem, but it does buy some time, while option 2 results in the formation of black markets in which the price of the ruble will fall more than it would were the government to revert to a flexible exchange rate.
What is the effect of having a fixed exchange rate which is greater than the equilibrium exchange rate? It makes it less expensive for Russians to buy foreign goods (so Russian imports are greater than they would otherwise be). It also makes it more expensive for foreigners to buy Russian goods (so Russian exports are less than they would otherwise be). Because GDP rises when exports rise and falls when imports rise, having a fixed exchange rate which is greater than the equilibrium exchange rate is bad for the economy. So, maybe devaluing the ruble is a good thing -- if the ruble is devalued to, say, 100 rubles = $0.75 then (1) the Russian central bank no longer has to buy up surplus rubles (because there won’t be any surplus), (2) Russian exports rise (because Russian goods are now cheaper for foreigners), (3) Russian imports fall (because foreign goods are now more expensive for Russians). According to this formula, Russia should be on its way to a burgeoning economy.
Not so fast. Many foreigners have purchased Russian bonds. These bonds are IOU’s that state that the Russian government promises to pay a certain amount of rubles to the holders of the bonds at some fixed date in the future. Suppose you are the IMF. Six months ago, you purchased 100 billion rubles worth of Russian bonds. At the fixed exchange rate of 100 rubles to $1, you paid $1 billion for the bonds. Let us say that the bonds yield 10% interest and come due tomorrow. You will have earned 5% on the loan. So tomorrow, you will receive a check for $1.05 billion, right. Nope. Those bonds were denominated in rubles. You will receive back your 100 billion rubles plus 5%, or 105 billion rubles. BUT, now that the government has devalued the ruble, those rubles trade not at 100 rubles to $1, but at 100 rubles to $0.75. The 105 billion rubles you receive tomorrow are worth $787 million and change. Because of the devaluing of the ruble, you just lost almost a quarter of a billion dollars -- and that is after accounting for the interest you earned. Thus, for the Russian government to devalue the ruble is tantamount to its defaulting on a portion of its debt.
Our story is not yet over. Combine all of the above with the fact that the Russian government has been ineffective in collecting taxes. Because it is ineffective in collecting taxes, the government does not have enough rubles to either pay off the debt it owes on its bonds or to purchase the products it requires to continue operating as a government. While the Russian government can devalue the ruble so as to eliminate some of the debt it owes, devaluation is not a panacea because: (1) the more the government devalues the ruble, the lower the probability that it will get another loan from a foreign government in the foreseeable future, (2) devaluing the ruble relieves the pressure of having to pay back debt, but it does not provide rubles for future purchases. In order to obtain rubles for future purchases, the government (absent tax revenue) has no choice but to "print" rubles. So, the government prints the rubles and buys the products it needs to stay in business as a government.
Not so fast. The average prices of products in a country is (roughly speaking) the ratio of the quantity of currency in the country to the quantity of products produced in the country. When the Russian government prints rubles, it increases the quantity of rubles without changing the quantity of Russian products produced. The result is that prices go up by the same percentage as does the money supply. But, because prices will rise only after the economy is aware that the government has expanded the money supply, if the government is quick to print and spend the new money, it will be able to buy what it needs with the new rubles before inflation reduces their value. Like a game of hot-potato, those who pay for the government’s purchase of product with "printed money" are the people who are holding rubles when the inflation hits.
To summarize: the current economic crisis in Russia is caused by a combination of factors. The government has been ineffective in collecting taxes which means that the government has to print money to buy what it needs. In an effort to escape the effects of the nearly world-wide economic collapse, investors want to buy strong currencies (like the dollar) and to sell weaker currencies (like the ruble). The flight to dollars causes the equilibrium exchange rate of the ruble to fall. The Russian central bank finds itself forced to sell off almost all of its stock of dollars in an attempt to support a now untenable fixed exchange rate. As the Russian government runs out of money to buy what it needs and the Russian central bank runs out of dollars to support the fixed exchange rate, two things are done: (1) the Russian government prints rubles (causing massive internal inflation), (2) the Russian central bank devalues the ruble (effectively causing the Russian government to default on its loans).
How could this disaster have been averted? One suggestion (which some economists have been advocating for over a year now) is to encourage the IMF not to bail out Russia. Economic forces are like the tides: if you are delusional, you might be convinced that you can stop them; if you are smart, you’ll realize that you can’t and do the best you can not to get dragged out to sea. Had the IMF refused Russia the loans it requested a year ago, Russia would have been forced to do the sort of thing it has recently done: devalue the ruble and print money. The difference is that the devaluing would have occurred when the Russian debt was much smaller than it is now, and the printing of money would have occurred when Russian prices were lower than they are now. In attempting to hold back the tide, we may have ensured that Russia, instead of starting the long trek for high ground while the water was still low, has a firm foothold on the beach just in time to be swamped by a tidal wave of economic collapse.