Nowhere as everything is priced in US$. In the 1970s, a US Treasury Secretary said to the Europeans and Japanese, ”Our dollar, your problem”.
Today, the US should say to China etc, “Our debt, your problem”.
“If I owe you a pound, I have a problem; but if I owe you a million, the problem is yours,” John Maynard Keynes
That’s provided all parties are more or less civilised. If the creditor is a gangster loanshark, then the debtor is in a world of hurt whether he owes $100 or $1,000,000. In the old days, unpayable debts were lawfully settled through slavery, confiscation of your children as sex slaves, indentured hard labour for 10-20 years etc. Debtors’ prisons were still common even up till the first half of the 20th century.
At country levels, it can be settled through confiscation or annexation of another country’s territories, going to war etc. Currently China is using it’s depreciating USD to buy up commodity sources and producers all over the world, buying gold and to a lesser extent buying commodity currencies. If pushed too far into a corner and Beijing calculates that the endgame will be high unemployment, social unrest and danger to the CCC, it will be a no-brainer to them to instigate a “wag the dog” scenario, demonise the US, re-direct the anger and unhappiness of the peasants towards US. Beijing will manufacture a saber-rattling crisis with Japan, the Korean peninsula and the South China Seas, to force the US to give concessions. The Americans have no more appetite for faraway and long-drawn wars of attrition, both in human lives and trillions of dollars.