Yesterday the U.S. Treasury announced sanctions against two Chinese shipping firms for violating ongoing sanctions against North Korea [TREASURY HERE].
With USTR Robert Lighthizer and Secretary Mnuchin set to travel this weekend to Beijing for ongoing trade discussion, the sanction timing complicates the dance with the dragon. Subsequently President Trump sends the following tweet:

Slamming China with sanctions (over DPRK dragon activity) while Beijing is showing the Panda mask (during Beijing trade negotiations) is not wise. If the Panda mask drops during trade negotiations to reveal the Dragon face, then ok. However, the majority of the West, driven by a misunderstanding of the China-DPRK relationship, does not know how directly a manipulative Beijing controls Pyongyang.
Taking aggressive sanction action against China could backfire with Beijing ordering those around Chairman Kim to test a missile.

President Trump and USTR Lighthizer know the nuance and subtlety needed in the dance with the dragon.  The larger issue of DPRK denuclearization, the bottom-line reason for the North Korea sanctions, will be solved within the U.S.-China trade discussion.
Of course the media, who have no concept of the dance with the dragon/panda; and no concept of Chairman Xi’s control over Chairman Kim; will jump in to say President Trump is only exhibiting short sighted egoism toward a relationship with Chinese Chairman Xi Jinping.  President Trump is doing exactly the opposite of being short-sighted; in fact he’s looking at the much larger picture.
The White House puts out a statement: “President Trump likes Chairman Kim and he doesn’t think these sanctions will be necessary.”  Again, President Trump is playing to the current Panda mask position of Chairman Xi, and positioning U.S.T.R Lighthizer’s upcoming trip to China without the controversy of recent sanctions looming over the negotiations.
In the dance with the dragon, all action must take place toward the face that is currently visible.  Beijing is currently showing the Panda face.  The U.S. Team know the Panda mask is just that, a mask.  This is one of the nuances in dealing with China.
It would be poor form, and ultimately result in little progress, to approach the Panda mask using dragon hostility.  This is not how successful outcomes against the Chinese are reached.
The dragon weapons, in this case brutal sanctions, are saved for when the Panda mask is visibly removed; and/or when the Chinese opponent knows you are aware of their duplicity.  Deploy countermeasures too early, and your give an excuse for the Panda to drop the mask.

When dealing with China all negotiations must come from a place where China gains something.  From the Chinese position if it does not benefit China; if it does not gain them value; it is not done.  If there is nothing positive to gain from negotiations, then no action is taken.
The outcome of negotiating to ‘lose less’ is not a position that China accepts.
President Trump already has the Chinese government controlled economy in a state of worry.  That worry keeps companies away from engaging with China.  That worry is a negative position for Beijing.  The elimination of that worry is a positive outcome.  China will negotiate terms if they can gain the value of eliminating economic worry.
Thus, the dance with the dragon.