I gave an economic presentation the other day and we were talking about how the Chinese devalued their currency to make their exports cheaper to the world, and essentially position themselves better to the American consumer. Someone asked me then why doesn't the U.S. simply follow suit. I answered that every country could not do this because it would end up being a zero sum game and that everybody would eventually lose and that it would not be sustainable. Furthermore, with the U.S. dollar the reserve currency of the world, the amount of volatility in the market place would skyrocket if the U.S. did the same thing. What else could I have said or is there another angle to tackle the question?
China’s total trade (exports+imports) as percentage of GDP is about twice that of the US. In this sense, the US is a relatively closed economy and therefore its monetary policy is (and ought to be) more domestically oriented. Second, Chinese trade with the US is only about 15% of the US trade with the rest of the world. Any exchange rate intervention by the US will thus also affect the rest of the world, so yes, any such step will force the other countries to follow suit and lead to a zero sum currency war as you rightly talked about.