» more from CNBC Explains

Biggest Holders of US Gov't Debt

As the U.S. government spends an unprecedented amount of money to fix the economy, there is an equally great need to raise the cash to pay for it. This is accomplished through borrowing, whereby Uncle Sam sells Treasury securities of varying maturity.

For investors, government bills, notes and bonds are considered safe because they have a guaranteed rate of return, based on faith in future U.S. tax revenues. The government has been partially funding operations via Treasury securities for decades.

This borrowing adds to the national debt, which has recently surpassed $15.7 trillion and is rising every second. The amount of debt is quickly approaching the federal debt ceiling, a legal limit to borrowing that currently stands at $16.4 trillion.

Much of that debt is held by private sector, but about 45 percent is held by public entities, including parts of the government. Here's who owns the most. Foreign countries listed include both private and public investors, according to monthly U.S. Treasury data.

By Paul ToscanoUpdated 31 May 2012

Photo: Getty Images