So, what you're saying is that Japan, China, the UK, Germany, France etc bought our debt out of the goodness of their heart and they can never cash in the Treasury notes they bought?
No, I said you haven't a clue what you're talking about.
T-bills can't be redeemed on demand. They have a specified maturation date, no greater than six months. When someone buys a Treasury Bill, they have only two options: 1) Wait for it to mature to collect the matured amount, or 2) Sell it to someone else, who will collect the matured amount. Now, the moment that those puppies mature, you can bet your bottom dollar that China et al are redeeming them. They don't let them just sit and serve as an interest free cash loan to the US. As you point out, they're not buying them out of the goodness of their hearts.
So, your contention is absolutely bogus. Even if China were sitting on $1 trillion of T-bills at any given moment, they could not simply redeem them on a moment's notice just to engage in a tit-for-tat over tariffs.
Furthermore, the contention that they
would change their investment behaviors in order to engage in a tit-for-tat over tariffs is itself ridiculous on its face. Again, I point out your own contention that they do not engage in these investment behaviors out of the goodness of their hearts. These are investment decisions, and they are made for the sole purpose of enhancing their own welfare and wealth. Investing in US debt is an exceptionally solid and safe investment, with a very strong return potential. When you can get an 8% APR with virtually zero risk involved, I dare anyone to back away from that.