Vyacheslav Dodonov, http://kisi.kz/images/izdanie/CAA_04_2018.pdf

The US government debt currently serves as the basis of the world reserve system - according to the IMF, 62.5% of the world's total reserves are stored in various types of US government obligations produced by the Federal Treasury [1]. On the other hand, foreign investors are also very important for the American public-finance system, since they own (as of July 2018) government obligations totalling $ 6,251 billion [2]. This represents almost 30% of total US federal debt ($ 21.2 trillion in the second quarter of 2018); and 41% of that amounts to $ 15.5 trillion [3], which accounts for investors (also a certain part of the US government debt belongs to government departments). Thus, the US national debt performs a very important function for the global financial system, acting as a core element of its reserve assets; but, at the same time, results in government finances depending highly on foreign holders of treasuries.