Import tariffs announced by the Trump administration threaten to spark a global trade war that could put a dent in the U.S. agricultural market—and domestic soybean prices could suffer the most.

U.S. trading partners world-wide have threatened to retaliate against tariffs on steel and aluminum and have voiced similar sentiments about previously announced import tariffs on residential washing machines, as well as solar cells and modules, earlier this year.

While China could pose the biggest threat to soybean prices, Canada and Mexico could target a broader array of agricultural products with tariffs. The two nations are exempt from the U.S. aluminum and steel tariffs, but U.S. threats to withdraw from the North American Free Trade Agreement have shaken its relationship with its neighbors, two of the U.S.’s biggest agricultural trading partners for products such as corn, pork, and vegetables. In 2016, U.S. exports of agricultural products to Canada totaled $23 billion, and to Mexico, $18 billion. Mexico is also the second-largest market for U.S. soybeans.

If the U.S. were to leave Nafta, it would probably weaken the Mexican peso USDMXN, -0.08% and Canadian dollar USDCAD, -0.03% against the U.S. currency, says Adam Koos, president of Libertas Wealth Management Group. The subsequent rise in the greenback “would make U.S. agricultural exports less attractive,” he says. The current tariffs that Canada and Mexico levy on U.S. goods would surely also rise from their current negligible levels, says Koos.

But in the event of an actual global trade war, China may have the best weapon of retaliation in the agricultural market: soybeans.

China “could easily levy their own tariffs on the cost of soybeans,” and since China is among the top U.S. agricultural importers, “such a tax war could create serious problems on domestic soil,” Koos says.

Global soybean imports are expected to reach 151 million metric tons this year, of which China will import 97 million, or 64%, according to Peter Meyer, senior director of agricultural analytics at S&P Global Platts. The two largest exporters of soybeans, Brazil and the U.S., are expected to satisfy almost 85% of total global import demand.

“U.S. farmers and trade groups are keenly focused on soybeans and China, as the Chinese are the largest single importer of soy in the world to satisfy feed demand for their massive pork production,” says Meyer.

So far this year, soybeans, corn, and wheat prices have climbed. Futures prices for soybeans US:SK8 and corn US:CN8 have each climbed by roughly 8% for the year to date, as of Thursday. Wheat US:WK8 was also up almost 8%. Among exchange-traded funds, the Teucrium Soybean fund SOYB, -2.10% has gained more than 5%.

But “if the assumption is that [China goes] after agriculture in retaliation, then one would expect [U.S.] prices to fall,” says William Martin, analyst at Bondurant Futures.

That could cut demand for agricultural goods coming from the U.S. and raise the amount of domestic stocks seen at the end of the year. He believes that fundamentals for soybeans are already negative and any added tariffs would add to the price pressures. He’s bearish on soybeans, with the global market facing large year-end stocks, and says the commodity could potentially see prices “a couple of dollars cheaper” at some point in the year.

But prices for soybeans, wheat, and corn may still be destined to rise long term. “If China, Mexico, or others looked elsewhere for their grain purchases, there would likely be a temporary dip in U.S. prices of grains,” says Sal Gilbertie, president and chief investment officer at Teucrium Trading.

Global grain prices, including those in the U.S., would then “very rapidly adjust to equilibrium, because there is too much global demand for grains, with too little excess supply for any price decline due to trade policy to be sustained,” he says. Global ending stocks for the 2017-18 growing season are predicted to be only about an 80-day supply for oilseeds, mainly soybeans; 132-day supply for wheat; and 62-day supply for coarse grains, mainly corn, says Gilbertie.

“Global demand for grains is increasing, which means the price dip would likely end up being a buying opportunity, unless demand mysteriously collapsed somehow,” he says.