I wouldn't call it "illegal", but international trade agreements define situations in which it is permissible to counter subsidies with retaliatory tariffs. Th

I wouldn't call it "illegal", but international trade agreements define situations in which it is permissible to counter subsidies with retaliatory tariffs. The EU has retaliated against the US's subsidies for Boeing before, although those tariffs are currently suspended. Tariffs to counter chip subsidies would likely be permissible as well.