Funding for our national budget includes tax revenues and borrowed money (domestic and foreign - yes, we borrow money from ourselves as a nation)

A nominal 6 trill dollars of our 20 trillion dollar debt is owned by foreign entities.  The remaining 14 trillion dollars is domestic debt to include the following.  

Understand that Obama used his raping of our military and domestic debt accumulation via the Fed and its Quantitative Easing policies  (buying high risk mortgages from the banks) to keep interest rates from rising.  This policy was a killer for middle class retirement funding via banks savings programs and 401k's,  for nearly a decade while making loan funding available (again and again) to corporations.  Throughout most of Barack's term,  money borrowed by the fat cats Democrats supposedly hated,  was almost free for the taking,  what with interest rates at or below 1%.  What was great for the fat cats was a disaster for the working man and middle folks.  401K's took it in the shorts .  Earnings today,  for 401K funds is at a 16 year high,  thank you Donald Trump.  Understand that the small community bank and savings and loan institutions failed more than they succeeded during the Obama years,  for the first time in American history.  The notion that the Barack's fiscal policies helped the little guy,  the forgotten man,  the middle class working man,  was and is sheer crap.  Lets agree not to back to the slave masters in the Democrat Party  ~  editor notes. 

Here's the breakdown of holders of the public debt as of December 2016:

• Foreign - $6.004 trillion (see "Foreign Ownership of U.S. Debt"  below.
• Federal Reserve Most of this debt the result of bailing out the mortgage industry and its "Affordable Housing" promises  causing the 2008 financial collapse - $2.465 trillion
• Mutual funds - $1.671 trillion
• State and local government, including their pension funds - $905 billion
• Private pension funds - $553 billion
• Banks - $663 billion
• Insurance companies - $347 billion
• U.S. savings bonds - $166 billion  (note "T Bills" have maturies of a year or less;  bonds mature over the course of 10 to 30 years,  typically  `  editor).
• Other (individuals, government-sponsored enterprises, brokers and dealers, bank personal trusts and estates, corporate and non-corporate businesses, and other investors) - $1.662 trillion.

Foreign Ownership of U.S. Debt

1.  China owns $1.2 trillion of U.S. debt.  

2.   Japan at $1.1 trillion. 

3.  Ireland is third, holding $326 billion. 

4. The Cayman Islands is fourth, at $270 billion. The Bureau of International Settlements believes it is a front for sovereign wealth funds and hedge funds whose owners don't want to reveal their positions. So are Luxembourg ($218 billion) and Belgium ($119 billion).  In other words,  we do not know which entities and "fat cat insiders" own this part of our debt.  These folks,  because of the deficit they own,  benefit from the interest owed to them and the financial/federal policies they control ~ editor

5 - 7 include:   Brazil, the UK,  Switzerland, Hong Kong, Taiwan, Saudi Arabia, and India. They each hold between $14 4and $257 billion. 

Source:  See the article by Kimberly Amadeo,  here.  
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Note:    Both Japan and China want to keep the value of the dollar higher than the value of their currencies. That helps keep their exports affordable for the United States, which helps their economies grow. That's why, despite China's occasional threats to sell its holdings, both countries are happy to be America's biggest foreign bankers.