In reply to: "The US owes China about 3.5 trillion dollars. What if China called in its debt immediately?"

If China decides to sell US Treasuries then US Fed will buy them. So instead of having 3.5 trillion interest bearing securities China will have 3.5 trillion dollars in cash, with no interest accruing. The Chinese are smarter than that.

Your other points are well taken. But selling US Treasuries will not do anything.