They're boxed in by their existing problems with capital flight due to money printing. If they dump T-bills, it makes their goods less competitive. If they devalue, capital flight resumes. Nowhere to go but war.

Meanwhile, the Russians did the sane thing in reaction to sanctions, and preserved the value of their currency by Dumping half their T-Bills.

And here's the smart case for what should be going on: Unilateral free trade.