Our national debt is really serious

Congressman Frank Wolf hosted one of his "Town Hall meetings" yesterday in Leesburg and not surprisingly he addressed the national debt in his opening remarks. Wolf is a lead sponsor on legislation that would offer a "SAFE solution" to our mounting federal debt, and has been pushing the legislation for some time now.
Wolf notes that the national debt has ballooned to more than $12 trillion, and that at the pace of current spending "could grow by a trillion dollars a year for the next 10 years." He's urging Congress to form a bi-partisan commission of experts who could recommend actions that would put the nation on track to bringing down the national debt, and keep it heading in that direction. His bill is "The Securing America's Future Economy (SAFE) Commission Act."
You and I have heard politicians rail against the increasing national debt as long as any of us can remember. Many congressmen (including Wolf) have attacked the national debt even as they work to secure government spending in their own districts. Wolf has been effective for us in helping with Northern Virginia's transportation problems, and others. And of course we all want even more help, whether or not the mounting national debt becomes more severe.
I've never worried much about the federal deficit until now, but recently I have become extremely worried! Here's why:
My introduction to the federal debt was during World War II when my mom and grandparents bought "War Bonds" to help fight the war, while my father and two uncles served overseas. The bonds earned interest at maturity; we could cash them and take the money, or we could buy more bonds.
This all worked very well because the government's debt was spread among its citizens.
But later -- while I certainly wasn't paying attention -- our federal legislators wanted to spend more than taxes and citizen bond-buying together could raise, and our government began selling bonds to others elsewhere in the world.
No problem. America was a safe investment. It wasn't going to default on its loans. Bankers and individuals and governments overseas were glad to buy U.S. bonds -- and our deficit continued to grow.
But recently I read that China owned what sounded to me like a substatial portion of our federal debt! CHINA! The nation that I think of as "Communist China" -- a nation that appears more than any other to be readying itself to challenge us as the world's acknowledged leading nation.
So I asked Wolf at his Town Hall meeting yesterday if that was correct. "What happens," I asked, "if China decides to call our loan?"
Wolf confirmed that we should all be concerned about having China as a lender. He didn't try to describe our national risk in detail -- but he noted that China could do that. And he noted a specific example in which the Eisenhower Administration threatened to call a foreign debt as successful leverage in international negotiations.
I wonder if today we could simply buy back the debt that we owe China.
What if we can't?
Maybe China sees our debt as simply a good investment, just as Swiss bankers do.
But I see a hugh difference between some of our national debt being held in Swiss bank accounts and having any of our debt held by the Chinese government.