From the Summary: "This report presents current data on ownership of U.S. Treasury securities and major holders of federal debt by country. Federal debt represents the accumulated balance of borrowing by the federal government. The gross debt is composed of debt held by the public and intragovernmental debt held by federal trust funds. To finance the publicly held debt, U.S. Treasury securities are sold to investors. Treasury securities may be purchased directly from the Treasury or on the secondary market by individual private investors; the Federal Reserve; financial institutions in the United States or overseas; and foreign, state, or local governments. As of December 2020, there was $21.6 trillion of publicly held debt outstanding, up from $14.4 trillion in December 2016, a $7.2 trillion increase. During the same period, foreign holdings of debt increased by $1 trillion to a total of approximately $7.0 trillion."
CRS Report for Congress, RS22331
Congressional Research Service: https://crsreports.congress.gov/