The notion of walling any country in these modern times goes against the grain of any cohesiveness gained or achieved by humanity.
A wall on the United States (US)/Mexico border - erected for whatever fallible claim its advocate might possess, implies malice.
A wall represents a bad ideology to separate people from each other based upon unfounded fear. And against the background of the torn down Berlin Wall from the times of the Iron Curtain, any US attempt to construct a wall on its southern border, certainly amounts to a betrayal of humanity and of democracy. The movement of people aspiring for a better life across any border is not intrusive upon a nation's national security.
History must harshly judge the builder of any wall to prevent the fair mingling and migration of people.
In lieu of any wall, bridges of cooperation should be cultivated toward the betterment of all humanity.