I think it is clear, however, that the current situation is more a reflection of private sector choices over a number of years than of government decisions, though of course to the extent that government policies have influenced private sector choices those government policies must share some of the responsibility.
At the heart of the issue, countries run up obligations to foreign investors when, in total, they are spending (consuming or investing) more than they are earning. Let me stress that government borrowing is not the issue today.