Yesterday, the US government tried to borrow $24 billion by selling a bunch of 30 year debt.
It was a huge disaster. In order to get enough people to buy, the rate had to dramatically increase. Even then, then primary dealers had to buy 25% of the debt. The primary dealer are the buyers of last resort who have to buy.
China, Japan, Saudi Arabia, Russia ... none of them are buying our debt. In fact, most are selling what they already have.
With few buying, the US government is borrowing more than ever. $1.5 trillion in the past 4 months and they announced another $1.5 trillion in the next 6 months. The US government will have to offer higher and higher rates to attracted lenders.