“The United States needs to keep in mind that Brazil is the leading power in Latin America, playing a crucial role in the region and in key sectors such as critical minerals,” said Mr. Pascual, who currently serves as vice president for energy and international affairs at S&P Global.

According to Mr. Pascual, reciprocal tariffs from Brazil would be damaging for both countries. Still, he acknowledged that negotiations have become more complicated due to the letter from Mr. Trump, which blends political grievances with trade issues. In the document—which opens by defending former president Jair Bolsonaro—Mr. Trump describes Brazil’s treatment of Bolsonaro as a “global embarrassment.”

“Trump has his own way of imposing tariffs,” Mr. Pascual noted. “He didn’t choose a more traditional mechanism like a quota-tariff system, where the rate increases based on import volume. This was a political judgment. A good diplomatic effort is needed so that both sides can explain their rationale and work toward a mutually beneficial solution.”

The 50% tariff on all Brazilian products, announced by Mr. Trump on Wednesday (9), came as a surprise. Ms. Pascual, however, said the move fits with Mr. Trump’s pattern of using tariffs as leverage. “Trump has used tariffs to advance other political objectives, claiming they support the U.S. economy. He’s even used them in immigration negotiations. But he won’t succeed without diplomatic steps,” he said.

In the letter to Brasília, Mr. Trump listed what he called “a fundamental violation of American free speech” as one of the reasons for his decision. Experts believe this refers to Brazil’s efforts to regulate Big Tech. They point to recent episodes, including the suspension of X (formerly Twitter) in Brazil after noncompliance with court orders, and fines imposed on the platform owned by Elon Musk. Another example was the February suspension of the video-sharing platform Rumble by Brazil’s Supreme Court, ordered by Justice Alexandre de Moraes.

On Thursday afternoon (10), President Lula said Brazil may resort to the Law of Reciprocity if negotiations fail to yield results. He criticized Mr. Trump’s letter, saying it reflected a “total lack of understanding” of the commercial relationship between the two nations.

Although President Lula has expressed a preference for negotiation, Mr. Pascual believes it is too early to tell whether diplomacy will succeed. “There are several areas where talks could move forward. Brazil might try to negotiate a delay in the implementation of the tariffs, which Trump has slated for August 1,” he said.