The EU decided to target bourbon for the same reason it chose to levy tariffs on motorcycles and denim: Bourbon and Harley-Davidson are produced in Kentucky and Wisconsin, respectively, which are not coincidentally the home states of the Republican leaders of both houses of Congress. Blue jeans, which are also on the EU's list of targeted goods, are produced in House Minority Leader Nancy Pelosi's home state of California.

When I asked bourbon sellers in London if the retaliatory tariffs have made an impact on their prices, all of them told me it's still too soon to tell, as the new tariffs haven't impacted their current stock. But other American products on the EU's list are already feeling the repercussions. Just days after the European tariffs were imposed, the iconic American motorcycle brand Harley-Davidson announced it was considering moving its production of EU-bound motorcycles to plants outside the United States. The Milwaukee-based manufacturer said it was necessary to avoid paying import taxes nearly five times higher than it was used to (the EU previously had a 6-percent tariff Harley imports, now ratcheted up to 31 percent). The brand sold nearly 40,000 motorcycles in Europe last year, making the continent its second-biggest market.

Trump responded to Harley's decision by accusing the brand of using the new tariffs as a pretext for moving production overseas. "A Harley-Davidson should never be built in another country — never!" the American president said in a tweet Tuesday. He elsewhere expressed surprise that "Harley-Davidson, of all companies, would be the first to wave the White Flag." After all, the white flag signals surrender in a war, and Trump had boasted that trade wars are not only good, but "easy to win."

Unlike Harley-Davidson, bourbon distilleries won't have the option of moving their production overseas. The reason: Bourbon simply isn't bourbon if it's produced anywhere else. Just as scotch can only be produced in Scotland and cognac can only be produced in France, Congress passed a 1964 resolution declaring bourbon a "distinctive product" that can only be produced in the United States. The overwhelming majority of that production happens in Kentucky.

It's perhaps because of bourbon's distinctiveness that some have downplayed the impact EU tariffs will have on the industry. Matt Bevin, the Republican governor of Kentucky, dismissed the tariffs as a "money grab" by the EU and claimed they would not change Europeans' drinking habits. "Europeans are still going to drink more bourbon this year than they did last year," he said last week. "They're just going to pay more for it because their government is going to take some of it."

But actual bourbon distillers in Kentucky aren't as optimistic. "[Europeans] are still relatively new bourbon drinkers and people's tastes in alcohol tend to be fairly fickle," Susan Reigler, an expert on Kentucky bourbon and past president of the Louisville-based Bourbon Women Association, told me. "They have a lot of choices, they don't have to drink bourbon. People in the industry are worried that after their couple of decades really cultivating overseas markets that this could be something that certainly slows that momentum."