Trump is on record for saying ANY business will receive a big tax by shipping products into the USA. It is not unique to Harley.
That's how I read it, too. Trump's not "targeting a private business". But in the new world of "build here what you sell here", an American vehicle manufacturer that builds abroad and ships here will be subject to a tariff, same as a German vehicle manufacturer. The Europeans need to follow the example of the Japanese and even the Koreans, who build mainstream models here, increasingly from American-sourced parts.
The Japanese and Koreans have largely approached the American market in good faith. The Europeans have not (and increasingly, neither has the Big Three, who've even started to import cars from China (Buick Endeavor). If it takes tariffs to get automakers to build here, then so be it.
I've bought cars from the Big Three all my life, but when my son needed a new compact car, we got him a Hyundai. The car was assembled here, with an American-built engine and an American-built transmission. NO model from the Big Three offered all that.
