Bernie Sanders' economic advisor, Stephanie Kelton, has a great answer to this question. She helped found the economic school of Modern Monetary Theory, which explains debt and modern money (off the gold standard post-1971) through a new understanding of what debt and money are. Realprogressivesusa.com is a major contributor to the MMT conversation if you want to read more.

Basically, money is the private sector's inverse of government's debt. It's all one big accounting sheet. Government "debt" is private sector surplus.

Calling it "debt" is misleading, because it isn't really owed. The only way to eliminate it would be by eliminating all money.

Course some countries do owe other countries money. We don't, not even China (we're in debt to them in the same way a bank is in debt to you for opening a savings account).