USA official debt of $17 trilion but unofficially, according to a Princeton studies, the US has $220 trillion unfunded liabilities, or...er, DEBTS (it manipulates data, just read Americal alternative financial media)
Do you know what it means to have debts? It means USA has $17 trillion (or $200 trillion) or OTHER PEOPLE'S MONEY. It has all that money, much of which is in the form of tanks and planes, in USA, not elsewhere. And those other people DO NOT want USA to default on those debts, because they want to make sure that USA pays them back (countries like China for example).