What does that mean?
It means that they think we may not pay back all of our loans.
And it makes sense, too.
Instead of holding the line by not granting any extension of the debt, the Republican Party in the house and senate allowed the debt limit to increase by $1 trillion. In exchange, they got vague promises that the overall spending of the federal government ill be cut by $1 trillion—using baseline budgeting, which means we are borrowing money we can never pay back, not in a trillion years.
Our nation is about to go the same way as all the great empires, and for the same reason. There is a large group of people that have attached themselves to the federal treasury, like a baby to the bottle, and we do not have the political will to cut them off.