In a recent talk Bernanke gave he said, "As currently constituted, the international monetary system has a structural flaw: It lacks a mechanism, market based or otherwise, to induce needed adjustments by surplus countries, which can result in persistent imbalances." He is trying to put the blame on "surplus countries" like China. But the real problem with the international monetary system is that it is based on the US dollar and there are no limits on the US as a "deficit country". There is nothing stopping the US from printing as much money as it wants and having a huge trade deficit. The only reason China has a trade surplus is that the US has a trade deficit.
People like to believe that their problems are due to others, so Bernanke and Obama saying the problem is due to China plays well in the US. But clearly China is not buying it.
As the US prints more money it exports some in exchange for real goods. Think about this, the US can run off some money (electronic or paper) and buy an oil tanker full of oil. How cool is that? The US can make some money, loan it to Goldman Sachs at 0.1%, who can then buy huge parts of Africa. There is currently nothing limiting this kind of thing. This US money made out of thin air can be used to buy up huge amounts of stocks on stock markets around the world and vast quantities of real estate around the world. This is a huge structural flaw in the world financial system.
When central banks backed their currencies with gold, any country that printed too much would lose its gold to other countries. As it lost gold, prices in both countries would naturally adjust to help keep it from losing more gold. And theoretically if it ran out of gold it could buy nothing else. The current system has no market forces to keep the US from just printing forever.
The world has been counting on the US to play nice and for most of the last 40 years this flawed system sort of worked. But now the US is printing at a rate of about $1 trillion per year. This is about the same as the $1 trillion per year the world spends on importing food. So to the world this is a very big number, even if Krugman thinks there should be $8 to $10 trillion in quantitative easing. My own feeling is that $1 trillion per year will be enough to force the world to stop using the dollar as the world reserve currency. At this point the US will have to export as much as it imports. It is used to importing far more than it exports. This will make things very hard for the US.