The Trump administration and the people who voted him in spoke very loudly in 2016 that the trade relationship with China must be fixed.
The Trump administration is simply righting the wrongs done in trade between America and China ever since the year 2000. The Trump administration is taking a defensive position to the trade war China was allowed to start on America after its ascension to the WTO in 2001.
How does a nation like China who has been practicing extreme unfair trade practices declare "retaliatory" measures against a defensive position? By doing what it has done in the past and manipulating the narrative when it comes to trade and its relationship with America.