The U.S. government is like anyone with a nearly maxed out credit card: the more debt the country accrues, the more it must pay in interest, which makes it harder to run down the original debt.
And the picture gets worse when the rates go up. That could happen to Uncle Sam if those who buy U.S. debt grow concerned about the country's ability to pay what it owes, or because inflation starts to erode the value of bond yields.
The end result: "Taxpayers have to pay more and more on the national credit card," says Robert Bixby, executive director of a deficit watchdog group, adding that the country paid $200 billion in debt interest last year alone.
Washington is also charging the cost of the wars in Iraq and Afghanistan to its national credit card. So far, the government has spent between $700 billion and $800 billion since 2001.