After China responded in kind to the initial $50 billion in tariffs, Trump added another $100 billion.
China didn't respond with a new in kind tariff because they don't buy enough. They import less than $150 billion from the US.
After gloating yesterday through their press that they had defeated Trump, claiming that he wouldn't risk the stock market to reduce Chinese import barriers, they are now shown to be unable to match Trump's tariff increases exactly. He also said there will be short term pain in the market.
This is rapidly escalating, and if China doesn't relent, it could finally push over their economy. All the outs for China currently floating around are actually their vulnerabilities. China being cut off from USD inflows is cutting off their life line.