On Saturday, in an effort to support local farmers and prevent the import of any genetically modified corn, Mexico initiated a 50% tariff on all imports of white corn.

Published in the Mexican government’s official gazette late on Friday, the tariff will take effect immediately and remain in force throughout the rest of the year. Its initiation comes amid a trade dispute over genetically modified corn between Mexico and both of its North American trade partners, the United States and Canada.

The Mexican government had exempted white corn from tariffs earlier in the year, along with other basic food items, in an effort to lessen inflation in the Mexican economy. However according to the published decree, that “has not generated a significant impact on the decrease in prices in the national market, so it’s considered appropriate to eliminate it.”

The Mexican government now considers inflation more or less satisfactory, after it came in at 5.84% in May.

Mexican imports of white corn, the variety used for human consumption, come primarily from the United States and South Africa. However given the new tariff violates the US-Mexico-Canada free trade agreement, it will exacerbate the trade conflicts the nation was already engaged in with the US and Canada regarding genetically modified corn.

Mexico wants to see genetically modified corn for human consumption restricted, and it wants to eventually ban genetically modified yellow corn used in animal feed. Both the US and Canada oppose such a measure, saying it will harm regional trade. Historically Mexico has imported about $3 billion worth of yellow GM feed corn from the US per year.

According the the United States and Canada, the fear Mexico has of genetically modified corn is “not grounded in science.”

On June 2nd, the government of the United States formally requested that an official dispute process be opened over the issue of genetically modified corn, after informal talks with the Mexican government failed to deliver any solution. Earlier in this month, Canada announced it would join in the trade dispute panel that the US had requested.

The dispute process will see a panel of experts take about six months to examine the complaint and render its decision on the matter. If Mexico is found to have violated the US-Mexico-Canada free trade agreement, the panel could elect to impose sanctions on the nation.

President Andrés Manuel López Obrador has said he is unconcerned with any controversy, and that Mexican citizens should only be eating white corn produced domestically in the nation.