oh gawd, our former hillbilly J.D.Vance has called the Chinese 'peasants', repeatedly. Hillbilly diplomacy at its best.
China is making this a big, hateful American cause celeb as big as the 104% tariffs due tomorrow.

China cannot unilaterally "call in" the U.S. debt it holds, as it's part of a contractual agreement with the U.S. government to repay the debt according to the agreed-upon schedule, just like any other loan.
However as long as Trump is breaking rules right and left who could say if China does the same and demands their money NOW. This could be a prelude to more than a financial tariff war if the Trump/Vance rude criminality continues.