China can't play the nuclear option. Same scenario as when you owe the bank $100 it's your problem but when you owe the bank $100 million, it's the bank's. Everyone knows the US can't pay its debt at current exchange rates but it can print money(devalue its fiat) to create jobs and get their consumer spending again and to fund its military complex which isn't there to police the world but ensure its future energy supplies. The rest is noise.