Having approached the NAFTA issue with very hardball tactics and striking at the sensibilities of the Mexicans with the implementation of the wall along the Mexican border, has increased tensions.
The implications of this approach with Mexico are not positive in a geopolitical sense since the current president of Mexico is weak and unpopular. This sort of rhetoric by Trump will fuel further support for the anti-American leftist populist candidate.
Unfortunately, the outcome of this populist discourse by Trump targeting his US domestic voter base will increase the chances of having an anti-American leader next door. In addition, this could invite closer ties with China or even the Russians if this leftist populist wins. That would be geopolitical disaster.