China is suddenly having debt problems of its own. Heavy recent lending by its banks comes as the recovery in the world's second-largest economy seems to be stalling. The export giant posted a rare trade deficit in March.
The national debt will soon be front and center again as a deeply divided Congress wrestles with an expected Obama administration request to increase the government's borrowing authority, the legislatively set debt ceiling.
The higher limit would not authorize borrowing for new spending but just enable the government to pay all the bills already racked up.
Yet despite China's relatively shrinking share of the U.S. debt, it continues to be the poster child for financing America's deficit spending habit, a favorite target for politicians in both parties.
It's not as if U.S. leaders approach China's bankers extending a tin cup and begging for loans. The Chinese government does what many individual investors do - it buys and holds widely available U.S. Treasury bills, bonds, and notes.
U.S. politicians see the mountain of debt, but investors globally view U.S. Treasury securities as among the world's safest financial havens, reflected in part by their super-low yields.
China held $1.22 trillion in Treasury bonds as of February, the most recent month available from Treasury.
The tally for the Fed and Social Security is about $4.4 trillion - over 25 percent of the total debt.
"China is neither an enemy nor a friend; it's a rival for economic success and for global influence," said Bob Sutter, an international affairs professor at George Washington University. "Americans dislike the Chinese government and they want to compete. But they don't want to confront China, and so they want to get along."