Daniel Gross dives into the figures:
Over the past few years, our dependence on China as a lender has declined in both absolute terms and in relative terms. For all those who say the U.S. doesn’t make anything the world wants, look no further than the Treasury’s monthly statement of the public debt, which can be seen here (PDF). We manufacture government debt. And the world buys it. In the recently concluded fiscal year, the deficit was about $1.1 trillion. Between September 2011 and September 2012, the grand total of marketable debt held by foreigners rose from $4.9 trillion to $5.455 trillion, or about $555 billion.
So, yes, the amount of debt owned by foreigners has risen in the past year. But the portion of the debt owned by foreigners has stayed about the same—at about 51 percent—and the portion owned by China has fallen sharply. China’s total holdings of U.S. debt are about where they were in the middle of 2010, when the volume of total U.S. debt was much smaller.