My goodness. Do you actually read the papers? Leo has said quite clearly that not one penny will be spent on border infrastructure. He also said that he would expect any such infrastructure to be torn down by "hand if necessary" Don't forget every single border area 6 +26 is Catholic majority. So do you want 21,000 Brit troops back. That's what it took. So the brits would build the checkpoints. The local catholics would attack them. See where this is going.As long as the physical checks are done inland away from the border and done on a statistical sampling basis, they will not unduly upset Irish nationalists and hence be practicable. Sampling would be enhanced when based on technologies for tracking goods and traffic on the border.