Group 1 - The total U.S. national debt has reached $36 trillion, nearly 1.5 times the GDP, with annual interest payments amounting to $1.1 trillion [2] - The largest creditors of U.S. debt are domestic individuals and institutions, holding 76% of the total debt, indicating a high level of "internal circulation" [3] - Major domestic holders include individual and household investors ($2.1 trillion), the Federal Reserve ($4.2 trillion), commercial banks ($3.8 trillion), and pension funds [3] Group 2 - International creditors hold about 24% of U.S. debt, primarily from Japan, China, and the UK, with Japan being the largest external creditor at approximately $1.07 trillion [4] - China has reduced its holdings by over $500 billion in the past decade, currently holding about $760.8 billion, making it the second-largest external creditor [4] - Other notable external creditors include the Cayman Islands ($397 billion), Saudi Arabia ($135.6 billion), and various European countries [5] Group 3 - The ongoing increase in U.S. debt and fiscal deficit has raised questions about the creditworthiness and safety of U.S. debt, influenced by geopolitical factors [5] - Major external creditors like Japan, China, and the UK have been reducing their holdings, while neighboring countries like Canada and Mexico are increasing their investments in U.S. debt [5]