The Chinese are doing everything they can to make sure US tariffs don't affect US consumers.
And discourage factory work to leave for other countries (Vietnam, Mexico, Taiwan, Thailand, etc).
And discourage factory work to leave for other countries (Vietnam, Mexico, Taiwan, Thailand, etc).
This large trade surplus basically means China earns a lot of USD and it uses those US dollars to buy US T-Bonds.
So for T-Bonds the USD/Yaun exchange rate does not come into the picture.
But that low USD/Yaun exchange rate does help to keep Chinese exports cheap and that then helps to protect their trade surplus.