The New York Times > AP > Business > Greenspan Says U.S. Deficits Pose a Risk

This could be a very BIG problem. "So far, foreigners are willing to lend the United States money to finance the current account imbalances, Greenspan pointed out. The worry, however, is that at some point foreigners might suddenly lose interest in holding dollar-denominated investments. That could cause foreigners to unload investments in U.S. stocks and bonds, sending their prices plunging and interest rates soaring."