President Donald Trump reiterated his intent to impose an extra $325 billion in tariffs on Mexican goods Friday, suggesting he was negotiating a trade deal rather than simply threatening America’s southern neighbor.

He also confirmed he still doesn’t understand how tariffs work.

“If we are able to make the deal with Mexico, & there is a good chance that we will, they will begin purchasing Farm & Agricultural products at very high levels, starting immediately. If we are unable to make the deal, Mexico will begin paying Tariffs at the 5% level on Monday!” he tweeted.

If we are able to make the deal with Mexico, & there is a good chance that we will, they will begin purchasing Farm & Agricultural products at very high levels, starting immediately. If we are unable to make the deal, Mexico will begin paying Tariffs at the 5% level on Monday!

— Donald J. Trump () June 7, 2019

Trump has been telling Mexico for several weeks that he will impose the tariffs if Mexico doesn’t do more to stem immigration from Central America. While Trump has been abroad on a state visit, the White House has been meeting with Mexican officials to discuss what steps the nation would be willing to take that would satisfy Trump’s vague concerns.

It is unclear what proposals have been discussed so far, though officials have confirmed that Mexico is sending its National Guard to its southern border to try to curb migration from Guatemala, one of the Trump administration’s central demands, which also include requests that Mexico keep all U.S. asylum seekers on its side of the U.S.-Mexico border and crack down on transnational gang activity.

As of Thursday night, however, the White House said it was still planning to move forward with the tariffs.

At no point has Trump previously said that the tariffs were related to trade. His tweet suggests that the price at which Mexico purchases farm equipment from the United States is a factor in the negotiation.

Trump also indicated in the tweet that “Mexico will begin paying Tariffs,” suggesting that his understanding of tariffs is still thin at best.

When Trump announced massive tariffs on China last month, he repeatedly insisted that China would pay the tariffs. In both cases, however, American companies shoulder the burden of the increases costs of the tariffs, which they then typically pass on to American consumers. Neither China nor Mexico pay anything when the United States institutes these tariffs.

Sen. Chuck Grassley (R-IA) tried to explain this to Trump in a letter last month, noting how much farmers in his home state of Iowa will suffer as Trump’s trade war continues. He chose a letter, he said, because Trump hasn’t listened when he’s explained tariffs to his face. “I’m not sure if you talk to him face-to-face he hears everything you say,” Grassley said last month.