They'll work to create massive inflation in America. 

Since America is the only buyer affected but the seller still has the rest of the world as customers it really is a self own.

Keep in mind for double stupid you are making this threat to brics countries, which means they are actively trying to uncouple their economy from the US economy already. This helps their goal. 

 Ex-china Brics countries will likely continue to impose and increase tariffs on china's exports as will many Global South countries who can not continue to absorb china's lack of domestic consumption.