Instead of reciprocal tariffs, Europeans should announce they will no longer honor US patents and copyrights. Or, wouldn't honor US intellectual "property" on its current absurd terms.
Tariffs on US goods would hurt European consumers. Dispensing with copyrights and trademarks from the US wouldn't. If the US retaliated, the balance of pain would still favor the Europeans.
The US billionaires supporting Trump make their money from intellectual property.