The FDA and the US Department of Agriculture are fighting over one innocent-seeming food item: Soy milk, and in particular, whether or not that’s the proper term for the plant-based drink. According to recently released emails cited in a report from the Ohama World-Herald, the US Department of Agriculture “fervently” advocated for the use of the term “soy milk,” drawing the ire of the Food and Drug Administration, which believes that picking a term to describe the beverage that comes from soy is “not a trivial decision.”

The Good Food Institute uncovered the emails, in which a nutritionist working for the Department of Health and Human services let the FDA know that the USDA planned to release educational materials to the public that use the term soy milk.

In the exchange, the FDA points out that they define milk as “lacteal secretion,” which means that almond, soy, rice, and coconut “milk,” can’t be correctly labeled as such. They suggested using the word “beverage” instead.

Though the FDA warned that continuing to use the term “soy milk” could undermine their authority, the nutritionist wrote that the USDA was “adamant about using the term in consumer publications” at the time.

Enter the National Milk Producers Federation, which is currently working on legislation requiring the FDA to enforce the federal standards for what can be considered true milk, while arguing that using the word "milk" is inappropriate when labeling non-diary, plant-based drinks.

The plant-based beverages industry is experiencing a boom right now: In 2016, the market was valued at around $7 billion; by 2022 it’s expected to be worth $14 billion. One of the driving forces behind that boom might be not just the varied applications of a beverage like coconut milk in products like yogurt and ice cream, but also the growing number of health-conscious consumers flooding the market.

The debate over soy milk has already been settled in the EU, where courts ruled in June that almond, rice, and soy beverages can’t be called “milk.”

Meanwhile, the FDA and the Department of Agriculture have not been able to decide on one official term for plant-based beverages. This may prove to an ongoing problem for the federal agencies, which haven’t been able to agree on what the term “natural,” means either.

This story originally appeared on Foodandwine.com.