Earlier today, China's premier expressed concern about its sizable holdings of Treasuries and U.S. debt. Premier Wen Jiabao asked America to safeguard the value of Treasuries, noting that China is ready to expand its stimulus if the economy gets worse.

According to Wen, China is the biggest foreign creditor to the U.S. -- causing the Premier to ask the U.S. to make sure that its response to the current economic environment doesn't harm the value of the Chinese holdings.

Why should you care what's going on in China? It makes many of the products we buy -- particularly the ones sold at Wal-Mart Stores (NYSE: WMT). And it has been recycling the profits it makes due to its relatively low labor costs into buying American debt. In fact, without its willingness to purchase our Treasury bonds, we would probably not be able to afford the $8.2 trillion worth of bailout plans that we've created so far -- or the additional $20 trillion we might need in the future.

If we were in the ninth inning of this financial collapse, instead of the second, then China's slowdown would not matter so much to our future. But if we need an additional $20 trillion over the next several years to put a floor underneath this economic collapse, we are not going to be able to rely on China to help foot the bill as we have in the last year. That's because China is slowing down; it has been growing at 12% a year for several years in a row, but that rate is likely to slow to at least 5.5%.

That would be a great growth rate for the U.S., but it represents a huge slowdown for China. Forty five percent of China's GDP growth is due to fixed asset investment -- like construction of houses and manufacturing plants. And a big part of that business is steel -- whose prices have lost 36% of their value since the peak, dropping from $768 a ton in June to a low of $490 a ton this month. One steel plant is cutting production by 15%. This means that global suppliers of commodities -- such as iron ore, copper, and cement -- around the world are suffering. What does this have to do with U.S. debt?