Al Capone would have been proud. Let’s end prohibition, it fuels violence and destroys respect for the law. And, no, I don’t and I won’t if it were legal.
If one googles the border crossing in SD..and move the screen along the border..you will see that there are relatively few structures that could conceal a tunnel. All these buildings should be legitimate business’s with little hesitation to give the BP access to the building without search warrants.
Frequent inspections would end the threat of tunnels. That is if they really wanted to end the smuggling.