BOGOTÁ — The best indication of Donald Trump's political clumsiness is his idea that the Mexicans will pay for the wall he would build if elected, in order to block northward migration through the U.S.-Mexican border.

Beyond the feasibility of walling off an entire 3,000-kilometer frontier, the proposal is both anachronistic and contemptuous of the principle of national sovereignty. It flies in the face of an international system built, for better or worse, on the idea that all states are equal in their sovereignty.

The border separating Mexico and the United States is not just one of the 10 longest in the world, but perhaps the most restless frontier of our time given the thousands of possible crossing points, both the legal and illegal ones. Fixed after a complex history of advances and retreats, and military, political and cultural strikes and clashes, it remains a highly sensitive crossing point. It not only separates two divergent versions of the New World, which are the respective heirs to New Spain and New England, but also clearly demarcates two worlds at different stages in their developmental progress.

Mexico and the United States have long played a difficult game in maintaining relations that are characterized by both proximity and distance, and which involve their governments and peoples. After the various phases of territorial claims, and their corresponding conflicts that naturally bequeathed a legacy of resentment, the neighbors now have an intense relationship via a frontier that both separates and joins them.

Anti-Trump protesters in Mexico City on Aug. 31 — Photo: Irvin Olivares/ZUMA

In terms of numbers, that means no fewer than 350 million crossings a year in both directions. It is also, unfortunately, the line crossed daily by thousands of people originating from literally every corner of the world.

Latino culture

Trump's proposal for a wall, and that Mexico should pay for it, is simple enough to show he has but a vague idea of the scope and dimension of the two states' relations. Among other elements he seems oblivious to the tremendous progression of Latino culture across the U.S., with Mexicans leading the way in this cultural transformation of so many aspects of everyday life there. A reminder of this increasing importance so bothersome to Trump is the fact that two of his strongest rivals in the pre-presidential race — senators Marco Rubio and Ted Cruz — were of Hispanic origin, and will continue to play an important role in the Republican Party.

Lost in the forest of his own rhetoric, Trump has said so many things that were later modified that many have even hoped he might substantially change his positions toward the Mexicans. This has not happened. Hours after his flash meeting with President Enrique Peña Nieto last month, the candidate repeated his wall proposal, speaking in Arizona, with the same initial conditions. Maintaining this threatening attitude, he loses credibility as a possible world leader.

If internal electoral contests become based on imposing obligations on other states, we would return to the most primitive instances of international relations. Why have we made so many efforts to build international institutions to assure the principle of non-intervention in state affairs, if we are to return to imposing arbitrary conditions on foreign countries?

The Mexican president has faced virulent criticism for inviting the U.S. presidential candidates for conversations, but it is Trump's ineptitude, when trying to win office in a country where Latin votes are so important, that should have become the object of condemnation. Because in addition to further alienating these voters, he is showing his ignorance of some of the essential traits of his southern neighbors. No Mexican president will accept paying for a wall, should this ever be built, nor will Mexicans permit it.

If Mexico has been consistent in one respect, it has been in its sense of national dignity. It is not something that any two-bit foreign politician can ever take away.