So, really, is there any doubt that this is true? China's currency exchange rate has been abnormally stable for a long time, and the Obama, Bush, Clinton, Bush, and Reagan administrations all knew it was the result of currency manipuliation. They just found it politically unpalatable to admit it out loud.
The real question would be, why is the U.S. finally admitting this out loud?
1) amping up a trade war
2) decoupling U.S. economy from China
3) trying to leverage China into doing something differently, perhaps regarding North Korea
Some of these, of course, would interfere with others, for example you can't use it as leverage in #3 if China thinks you'll keep pursuing it anyway no matter what, due to #1 or #2.
The real question would be, why is the U.S. finally admitting this out loud? 1) amping up a trade war 2) decoupling U.S. economy from China 3) trying to leverage China into doing something differently, perhaps regarding North Korea
Some of these, of course, would interfere with others, for example you can't use it as leverage in #3 if China thinks you'll keep pursuing it anyway no matter what, due to #1 or #2.