For the first time in several years I crossed to and from the border with Mexico, at Tecate, last week. Given my experience doing so, I found myself wondering whether we can even say we have a border with Mexico. Although there was an x-ray machine operating to get into Mexico, the Mexican immigration agent charged with screening luggage was too busy helping U.S. tourists move their bags off of the machine to bother even looking at what the x-ray images revealed. No big deal, a U.S. citizen might think, except that individuals who can so easily enter Mexico at another entry point may then attempt to enter the U.S.

Coming back in to the U.S., none of my bags were x-rayed, nor were those of any in the group I was traveling with. Of course, we all submitted our passports for review, but the x-ray machine was not used for anyone. Perhaps that is because we were all U.S. citzens, but I found myself wondering whether not x-raying anyone’s baggage was any worse than x-raying bags but not reviewing what the x-ray revealed. My conclusion is that both Mexico and the U.S. have a problem, as it is in both nations’ interest that border crossings be managed effectively.

Borders are the geographic boundaries of political entities or legal jurisdictions that are either completely open (such as in the Schengen Area of Europe), completely closed (such as with North Korea), or fall somewhere along the continuum between the two (as most do).

The border between the U.S. and Mexico is clearly on the more open end of that continuum, with most of the border being completely uncontrolled, given its 2,000 mile length. The U.S./Mexico border happens to be the most frequently crossed ‘controlled’ international boundary in the world, with approximately 350 million legal crossings being made annually. Perhaps that is why some customs and passport control agents on either side of the border don’t fuss too much.

In speaking with some people in Mexico while I was there, I learned that some of them had driven into Mexico from the U.S. without so much as a passport check. Even worse, two American citizens I spoke with had driven back and forth across the border back into the U.S. without having their passport, bag or person checked. This is occurring not only 15 years after 9/11, and after having spent many billions of dollars to enhance our security protocols and capabilities, but while the debate rages in the U.S. presidential campaign about the security risks associated with what can only be referred to as our “porous” southern border.

I don’t like much about Mr. Trump, but he sure has it right that the U.S. has a serious problem with its southern border. Beyond being outrageous that the above- referenced events could occur — even on a random basis — the idea that it may not be so random, but rather, the norm, makes my blood boil. Given the intention of a variety of terrorist groups to attack the U.S., you’d have to wonder why it hasn’t happened with greater frequency. You don’t have to be a conservative, or subscribe to the tactics of Sheriff Joe Arpaio or border vigilantes, to find the current state of affairs unacceptable.

Given that the ‘solution’ the Mexican and U.S. governments have crafted is so obviously inadequate, I find myself asking why building a border wall between the two countries should be so automatically opposed by people in the middle or on the left of the political spectrum. Are they truly willing to sacrifice their individual, and our collective, security for the sake of the civil liberties of people who enter the U.S. illegally, want to sell drugs or weapons, or engage in acts of terrorism? It seems to me that those who enter legally should have no reason to object.

Whether a border fence that is nearly 100% effective (as in the case of the fence separating Israel and Gaza) can even be constructed is questionable. Building such a wall could cost as much as $8 billion, and even if it were able to be built legally (current international and environmental law raises question about that), it is unlikely to be truly effective, given that passage between the two countries also occurs by sea and air, that drones are being used with increasing frequency, and that tunnels can be built to bypass the border. At least 40 such tunnels that have been discovered since 9/11, enabling the large-scale smuggling of drugs, weapons, and immigrants to take place. One tunnel running from San Diego to Tijuana was half a mile long, 60-80 feet deep, had a concrete floor, drainage, and was wired for electricity. It is hard to detect or combat that.

Would the construction of an 18-foot high concrete fence running the length of the border greatly disrupt the flow of illegal people, drugs, and weapons into the U.S.? Certainly. Will it be 100% effective? Certainly not. Would we be better off with it than without it? Probably. But building such a fence would make no sense at all if it was not accompanied by strict border protocols on both sides of the border. In that regard, building a fence would undoubtedly prove to be the easy part. I’d like to hear what Mr. Trump proposes for the rest of the equation. If that were already being done more effectively, there would be no need for a fence at all.