It's time for all bottleneck materials and components controlled by China to stop heading towards the US, in addition to secondary sanctions on any resellers trying to circumvent the export ban.
Isn't US effectively sanctioning itself now?
China's problem with the tariffs is that in the long term, Beijing expects to use the US market as part of its overall profiteering. But this isn't a short to medium term concern.
The purpose of new sanctions would be to keep dropping US living standards to encourage surrender. The method would mainly be by not letting Chinese companies sell to US (or US friendly companies). Well guess what's gonna happen now anyways. There's a reason US finance/economy took the news so badly...
Imo rather than sanctions China should look into asset forfeiture. Put a special income tax on the companies from US and any country willing to concede anything to US. Like for example now every time Apple makes 10 billion, 3 billion of that is not allowed to be transferred out of China. Same goes for any country who wants to transfer money to USA, you'll pay extra/earn less from any of your interactions with China.
The really questionable thing is that if China sanctions, US people will be rallied because Xi Jinping told them they can't have X necessary product. But with Trump's economy "reform", people will be rallied against the own government instead because Trump told them they can't have X necessary product. The outcome is the same. Of course I don't think US can rally to become effectively self sufficient, but Trump sorta makes things very easy for Xi here.