Mexican President Andrés Manuel López Obrador (AMLO) wrote a letter to the expected Republican candidate, Donald Trump, telling him that closing the border if he wins the November election could start an “opposition” on each side.

AMLO, who considers Trump a “friend,” stated that whereas he recognizes the remarks are related to an electoral campaign, it is crucial to note that our economic cooperation is so wide and extensive that coming to such a choice could be comparable to asking for a rebellion on each side of the border provided the harm it could bring to individuals, sectors, and business.

He also mentioned that the previous year, Mexican migrants provided $325,000 million to the country’s GDP, with $63,000 million transferred home as wages. That is, individuals pay 18.5% back and keep 81.5% of their earnings in the United States. Furthermore, he currently stated that he believes Trump is not “correctly aware of the migrant issue and the significance of preserving economic integration among the United States, Mexico, and Canada.”

The note comes as Trump ramps up his campaign in front of the November elections, with regulation of immigration as a key talking topic. The former president claims there is a migrant “invasion” and promises to execute the “biggest immigration operation” in the history of the US.

Current statements by Trump inspired an answer from Mexican President-elect Claudia Sheinbaum, who seemed to criticize Marcelo Ebrard, a senior official in the present government who will be her Economics Minister when she starts office.

Trump’s remarks were made this past Saturday at a rally in Grand Rapids, Michigan. He recounted discussions he made with the López Obrador government about immigration while he was president. “We were extremely hard on Mexico while I worked on the wall,” he said. “I stated, you’ve got to provide us 28,000 troops, and they giggled at me,” Trump claimed, it motivated him to make threats to impose tariffs on Mexican goods approaching the US.