Canada, Japan and Europe hold trillions in some kind of bond. Once they decide to call those in, it’s game over for the USA. Trump was made aware this was about to happen and had to stop - but he didn’t really. They can still do it, if he continues. Also China has a controlling interest in lots of US infrastructure/utilities, and controls a lot of the US loans/borrowing. This saga is by no means over. I hope Trump continues on the tariff path and all those monies are called in. He’ll only stop this if he’s personally affected. If it can be passed on the US people, he won’t care: but they will eventually take their revenge on him and his associates. Buckle up. It’s going to get nasty.

Yeah, they're basically debt - a good faith IOU sort of thing which allow governments to keep borrowing money. There isn't any *real* money anywhere, except gold, which afaik doesn't come close to covering the numbers on screens in value.
He'll wake up in a few days, or weeks, and decide one country or another has pissed him off, and it'll all start again. And it doesn't look like govts (apart from China and maybe Japan) are gonna do much about it.