Well golly gee, what a suprise.
Yet we have people who think a fence will solve our problems.
Now, if we dig it deep underground and make sensors to detect this sort of thing, it would work. But, how long would that take to build and at what cost?
This is true, and we do have sensors which could detect it. It is simply a matter of how much we wish to pay for it. We could make it a bit tougher if we had double fences.. seperated by a considerable distance, and allowed no development right up to the border... at least on our side. This would not solve it, but would at least make them dig a little further. Whatever the case, we could definitely figure out some things to make it a lot tougher with some good ole American ingenuity.