In the past, U.S. government debt was owned mainly by countries that were considered friendly toward the United States (like Japan), but now there is concern that the situation has changed as countries such as China and many oil-producing countries (e.g., Saudi Arabia) have acquired an increasingly large share of the U.S. government debt. Explain whether it matters how friendly the owners of this debt are to the United States. Could an unfriendly nation punish .the United States-if so, how and if not, why not?