As of May 26, 2016, total U.S. government debt outstanding was $19.2 trillion. Not only is U.S. debt held by various countries, it is also held by various U.S. government entities.
As oddly as it sounds, the single largest holder of U.S. government debt is the U.S., through its numerous agencies and departments. Contrary to popular belief, less than a third of all U.S. government debt is owned by foreign countries, not the purported fifty percent plus. There are two basic categories of debt; public debt which includes foreign and domestic investors, and federal accounts which are also known as intergovernmental holdings. Federal accounts currently total $5.32 trillion of all government debt and made up of 230 Federal Agencies. The agencies range from the mammoth Social Security Administration with over $2.7 trillion in bonds, to the Department of Energy, Office of Personnel Management, and the Department of State.
Foreign countries holding U.S. debt total roughly $6.17 trillion, with China and Japan being the two largest owners. As of March 2016, China owns $1.2 trillion of U.S. debt, while Japan has $1.1 trillion.
For the first time ever, the U.S. debt held by Saudi Arabia was released by the Treasury Department in May. It was previously part of the “oil producing nations” category of holders, which didn’t detail the amounts for each country. Saudi Arabia currently owns about $117 billion of U.S. debt, less than India, Taiwan, Belgium, and a host of other countries. Saudi Arabia has previously claimed that it held upwards of $750 billion of U.S. debt, and had used that as a diplomatic tool in dealing with U.S. officials.
Sources: Treasury Dept., Federal Reserve