A small amount of selling T-bills from bond vigilantes already caused Trump to drastically pull back his plan once. If a holder as large as China started a big dump of T-bills it would cause a massive financial disaster. China would feel some pain too, but the US having far higher interest rates as it rolls over new debt into new T-bills would be extremely difficult for us. We are at economic Mutually Assured Destruction levels this is still a lever that China can pull that is in their favor.