This piece from Newsweek by Jacques Attali is a good summary of the origin and growth of public debt. The use of public debt by the ruling classes to amass power and wealth cuts across all ideology and forms of government.
Two things are clear: Once a country achieves a certain level of debt, default is inevitable. The default is most often accompanied by war. implosion, and/or revolution.
The seeds for sovereign debt default are everywhere in the West plus Japan. In the previous post, I posited that the trigger for the default of these debts would be the loss of reserve currency status by the US dollar. Most world trade is financed by the dollar, and there is no ready replacement for it. The "basket of currencies" proposed by China, Russia, and the Arab states is mostly made up of currencies that are likely to suffer debt default or are not freely traded. The basket is not a ready subsitute for the dollar.
Global trade would shrink in the short to medium term, because of the lack of international credit. The twin deficits of the US would exacerbate our problem. The cost of imports would soar, and the normal export growth would be stymied by weakened international trade.
The US is in a politically weak position to respond to this crisis. The recent election did not create a constituency for radical reform. Mainly, it was a demand for the reinforcement of the status quo. It will take more economic hardship or another election to create the necessary public support.