Vicente Fox, formerly president of Mexico and currently a frequent critic of Donald Trump, told CNBC on Monday that the southern border wall proposed by the U.S. president serves "no positive purpose."
"The building of a wall is the stupidity out of the mind of Trump," said Fox, who was Mexico's leader from 2000 to 2006. "It's just isolating the United States from the rest of the world."
Trump has been calling for a wall on the United States-Mexico border since he launched his candidacy for president. Trump has argued repeatedly that a wall would secure the border and prevent illegal immigration.
That's a theme the president echoed in a Monday morning tweet, while calling for Mexico to tighten its immigration controls as a condition for finalizing an updated NAFTA.
The U.S., Mexico and Canada are in the throes of negotiating an overhaul of the 1994 North American Free Trade Agreement.
Fox said Trump's tweet is just a maneuver to try to "impress his base" of supporters. The former Mexican president predicted success in crafting a "better NAFTA" for all three countries. He spoke with CNBC's John Harwood from the eMerge Americas technology conference in Miami Beach, Florida.
Despite Trump's rhetoric on trade, the exchange of goods and services does not have to be a zero-sum game, Fox said.
Meanwhile, Fox said he has never met with Trump and won't meet the U.S. president unless he apologized to Mexico for all the disparaging remarks over the years, including part of the speech that launched his presidential candidacy in 2015. At the time, Trump called Mexican immigrants "rapists" and accused them of bringing "drugs" and "crime" to the U.S. He also said, "Some, I assume, are good people."
"Every time he opens his mouth, his big mouth, same thing, back to the past, back to a national state, back to the grandeur of America," Fox said of Trump. "America has been great always. It will be great forever. It doesn't need Trump."
The White House did not immediately respond to CNBC's request for comment on Fox's interview.