I see some U.S. commentators genuinely puzzled by AMLO's visit, considering Trump's open hostility towards Mexico. But there are a few things to keep in mind to understand this:

1/ https://twitter.com/phhamm33/status/1280905229698052097

First, the call to deny Trump’s legitimacy by “not normalizing” him as an interlocutor, is a strategy unique to American Liberals. Mexican authorities and citizens are mostly unfamiliar and uninvested in this idea.

2/

Not only is "not normalizing" not an option when dealing with the actual head of State of the US. But, from a Mexican perspective, there is no big difference between which American political party is in power 3/

The border wall that *already exists* began to be built during Clinton (and continued through all subsequent admins); Obama presided over a record number of deportations. Even the pressure for Mexico to patrol its southern border is not Trump’s innovation(e.g.Merida Initiative)4/

Second, AMLO is playing to a domestic audience. A recent poll showed that close to 60% of Mexicans support the trip. The renegotiation of NAFTA under highly unstable conditions was an important achievement. AMLO sees in his visit an opportunity to claim this as a victory 5/

After all, a significant part of the new agreement is a labor reform in Mexico that would facilitate unionization. Previous Mexican negotiating delegations often pushed against these clauses (promoted mostly by Canadian counterparts under pressure from organized labor)...6/

...arguing that low wages and precarious labor rights were their comparative advantage to attract investment. AMLO managed to use the re-signing of the trade agreement as leverage to secure the support of Mexican elites for the pro-worker reforms. 7/

Finally, Mexico has evidence that diplomatic pragmatism gets more results than public confrontation. Prominent examples of this include the U.S. recently stepping in to help Mexico meet the quota of reduced oil barrel production per day as part of an OPEC Plus agreement ...8/

...the securing of at least a thousand of ventilators for COVID patients, and avoiding Safe Third Country status that would have automatically prevented Central-American migrants already in Mexico from soliciting asylum in the U.S. 9/

These are not minor feats; all involved sustained communication. Of course, the trip is not without risk. Trump’s volatility and his own political maneuvering could derail things. But AMLO’s visit then is no puzzle, just the realpolitik calculations of a seasoned politician 10/10