By definition, Brexit puts a border between UK and Ireland
The recent speech by the British prime minister tells us what too many people have been trying to cover up, ie, that Brexit is a momentous decision with enormous implications not alone for the UK but also the EU - and not least for Ireland.
The Brexit vote could be the beginning of the break-up of the UK. But the implications go much further than that. It also could be the start of the dismantling of the EU. The EU is a unique union of nearly 30 European democracies, each of which, after centuries of imperial and totalitarian warfare, signed a treaty to co-operate in matters of mutual interest.
The UK is tearing up that treaty. In relation to Ireland, Brexit is a re-declaration of the economic war of the 1930s. At best, the Brexit vote will have a deleterious effect, as yet undeclared, on the billion-euro trade between the two countries on these islands.