The U.S. government issues Treasury securities to fund the deficit between the amount of money that it takes in through taxes and other sources, and the amount of money that it spends on defense, welfare programs and the interest it pays on its current debt. For 2016, the Congressional Budget Office (CBO) projects that the U.S. government will take in $3.4 trillion in revenue, while having outlays of $3.9 trillion, leading to a budget deficit of around $500 billion. The previous deficits combined with the $500 billion deficit for 2016 will put the government's total debt at around $19.4 trillion. U.S. entities, including banks, mutual funds, state and local governments, the Federal Reserve and Social Security hold about 68% of this debt, with foreign countries holding the remainder. So which countries hold the most?

China

China gets a lot of attention for holding a big chunk of the U.S. government's debt and for good reason. China takes the top spot among foreign holders of U.S. debt with $1.24 trillion in Treasury holdings as of June 2016. China trimmed its holdings 2.4% year-over-year, making it an owner of 6.4% of the total U.S. government debt and 19.8% as a percentage of total foreign holdings.

Japan

Japan is not far behind China as a big owner of U.S. debt, with $1.15 trillion in Treasury holdings, making it the second-largest holder. Like China, Japan also trimmed its position year-over-year but to an even greater extent. Japan's holdings fell 4.1% from $1.2 trillion in June, 2015. Japan now owns 5.9% of the total U.S. debt and 18.3% as a percentage of total foreign ownership.

Ireland

After Japan, there is a substantial drop off in the value of Treasuries held by foreign countries. Still, Ireland is surprising as the third-largest holder of U.S. debt among foreign countries, with $271 billion in Treasury holdings. To put this in perspective, Ireland is not even one of the top 10 economies in the world as measured by gross domestic product (GDP) but is the third-largest holder of Treasuries. China and Japan, on the other hand, are the second- and third-largest economies in the world as measured by GDP, respectively, which correlates with their fractional ownership of U.S. debt. Ireland, on the other hand, is the 41st largest economy with respect to GDP.

Ireland also significantly increased its holdings of U.S. Treasuries since June 2015. With an additional $53 billion in U.S. debt, Ireland bumped up its holdings by 24.3%. Ireland now holds 1.4% of total U.S. debt and 4.3% as a percentage of total foreign holdings.

Cayman Islands

Another surprising top holder of U.S. debt is the Cayman Islands — the fourth-largest holder of U.S. debt among foreign countries. The Cayman Islands is actually a British territory but is largely a self-governing, autonomous island. Known for being a tax haven and the legal home of many corporations, the Cayman Islands holds $269 billion in U.S. debt, representing a substantial increase of 21.8% year-over-year. The small island now owns 1.4% of total U.S. debt and 4.3% with respect to total foreign holdings.

Brazil

Brazil, home to the most recent Olympics in Rio, is also home to a large amount of U.S. debt. Like Ireland and the Cayman Islands, this South American nation is another country that "punches above its weight," by being the fifth-largest holder of U.S. debt among foreign countries, while having the ninth-largest economy in the world. Brazil trimmed its holdings 1.8% year-over-year and now holds $252 billion in Treasuries. Even with the decrease, Brazil holds 1.3% of total U.S. debt and 4% of total foreign holdings.