OMAHA (DTN) -- Stocks and grain commodities fell Monday after President Donald Trump posted letters on social media to the presidents of Japan and South Korea declaring 25% tariffs on products from both countries.

The letters, however, were the first part of an effort to delay the Trump administration's self-imposed July 9 deadline for other countries to reach trade deals. Karoline Leavitt, the White House spokesperson, said Monday that 12 other countries would receive similar letters. Trump would sign an executive order to extend the deadline for reaching a trade deal to Aug. 1, she said.

"So, the reciprocal tariff rate or these new rates that will be provided in this correspondence to foreign leaders will be going out the door within the next month, or deals will be made," Leavitt said. "And those countries continue to negotiate with the United States. We've seen a lot of positive developments in the right direction, but the administration, the president and his trade team want to cut the best deals for the American people and the American worker."

This week had been billed as a big one for the Trump administration's trade agenda as White House officials have repeatedly said there are dozens of trade agreements expected to be announced.

Most major stock indexes fell more than 1% on Monday. September corn fell 16 cents a bushel while November soybeans fell more than 28 cents. September wheat dropped more than 8 cents.

Trump posted essentially identical letters to the presidents of South Korea and Japan citing the countries will face a tariff of "only 25% on any and all" products sent into the United States. The letters each added the 25% tariff "is far less than what is needed to eliminate the Trade Deficit disparity that we have with your country."

If Japan or South Korea raise their tariffs on U.S. products, the U.S. will raise its tariffs as well, the letters stated.

The letters repeatedly listed the problems with trade deficits and their impact. "This Deficit is a major threat to our Economy and, indeed, our National Security!"

Leavitt said other letters to foreign leaders would also be posted to Truth Social.

Japan is the No. 5 market for U.S. agricultural exports and South Korea is No. 6. Last year they came in behind Mexico, Canada, China and the European Union-27 as top markets for commodities, according to USDA.

Agricultural exports to Japan in 2024 were just under $11.9 billion. For the first five months of this year, export value was up 5% over the previous year.

Agricultural exports to South Korea were $8.5 billion last year and the value of ag exports through the first five months of the year were up 15%.

Trump also has warned his administration would add a 10% tariff on all countries tied to BRICS -- Brazil, Russia, India, China, South Africa, Egypt, Ethiopia, Indonesia, Iran and the United Arab Emirates.

"Any Country aligning themselves with the Anti-American policies of BRICS, will be charged an ADDITIONAL 10% Tariff. There will be no exceptions to this policy. Thank you for your attention to this matter!"

India, however, is considered one of the countries the Trump administration has targeted to reach a major trade deal. According to press in India, agriculture has been one of the biggest sticking points as farm groups in India caution against opening up the country's market to U.S. commodities. Right now, India only accounts for about $2.3 billion in U.S. agricultural sales.

Chris Clayton can be reached at chris.clayton@dtn.com

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