Trump up until yesterday was using the strength of the US market...

Trump up until yesterday was using the strength of the US market as a barometer of the strength of his personal economic credentials. It seems inconceivable that suddenly he will throw that to the wind, undermining his huge push for a second term.
So my only reasonable conclusion is that he is trying to game the Chinese, to accelerate the progress of the trade negotiations to the endpoint that he desires.
The cash market was going to lose around 1.5% to 2% if the overnight futures were an accurate guide, but the steady recovery during the day to around a 0.5% dip, indicated that traders see his tweets as not something set in concrete. Now it will be really interesting to watch how this weeks Sino US talks progresses US interests, significantly further, or not. We are all looking for more certainty, but the Chinese do have more to lose, if it just goes all pear shaped.