Take Vietnam, a TPP member that increased American spirits imports by 173.9 percent between 2015 and 2016, to $45.9 million, making it the category’s fastest-growing importer. Under the trade deal, the country is expected to drastically increase its American whiskey consumption.

Without American membership in the TPP, a 12-nation pact that created zero tariffs for American products, Vietnam’s 45 percent duty on bourbon and other distilled spirits will no longer be phased out, putting those expectations on ice.

It’s not just about tariffs. When you’re selling “America” abroad, you need deals in place to make sure no one else is copying the brand. But absent trade agreements, other countries are free to sell their own versions of American products. Like Champagne and cognac, bourbon’s name protection relies largely on trade deals that set standards and definitions; without them, foreign distillers are surely tempted to slap “bourbon” on anything they want.

Trade deals also create structures to combat counterfeiting, another big problem for exporters. Asian countries already pose a great counterfeit risk for iconic brands like Jack Daniel’s Tennessee Whiskey and Maker’s Mark. While the TPP would not entirely have curbed this problem, it would have given American companies distilling the real thing stronger legal protection.

Of course, the TPP is not Mr. Trump’s only target. The president wants to renegotiate the North American Free Trade Agreement and possibly impose a 20 percent tariff on Mexican products.

Again, this hits the spirits industry in surprising ways. Like many successful American companies, distillers are globally diversified. Heaven Hill and Sazerac, which make Evan Williams and Buffalo Trace bourbons, are family-owned companies with deep roots in America that at the same time have a big overseas reach, importing or owning foreign facilities and marketing tequilas, rums and vodkas, as well as other whiskies.

Since tequila cannot be produced in the United States — it has a geographical protection similar to bourbon’s and can be made only in Mexico — Mr. Trump’s trade policy will damage American businesses that own, import or market tequila. And if we pull out of Nafta, expect to see a proliferation of Mexican distillers suddenly pumping out “bourbon.”