Attack on the US dollar
One of the pillars propping up US superpower status and worldwide economic dominance is the dollar being accepted as the predominant reserve currency. Central banks of various countries have to stock up dollar reserves because they can only buy their oil requirements and other major commodities in US dollars.
This US economic strength, however, is a double-edged sword and can turn out to be America's economic Achilles' heel.
A run of the US dollar, for instance, which would cause a dollar free-fall, can bring the entire US economy toppling down. What is frightening for the US is the fact that China, Russia and Iran possess the power to cause a run on the US dollar and force its collapse.
China is now the biggest holder of foreign exchange reserves in the world, accumulating $941 billion as of June 30 and expected to exceed a trillion dollars by the end of 2006 - a first in world history. A decision by China to shift a major portion of its reserve to the euro or the yen or gold could trigger other central banks to follow suit. Nobody would want to be left behind holding a bagfull of dollars rapidly turning worthless. The herd psychology would be very difficult to control in this case because national economic survival would be at stake.
Source:http://www.atimes.com/atimes/China/HJ19Ad01.html