Anyone who wants to make peace, diplomats know, has to throw down honorable principles and make unprofitable compromises. This was also the case with the Good Friday Agreement: Northern Ireland remained formally part of the United Kingdom, which the Protestants demanded, but with an open, invisible border with the Republic of Ireland, which accommodated the Catholic desire for reunification.
But this solution was only possible within the EU. Brexit destroys this constructive ambiguity. How much this move endangers the fragile Northern Ireland peace became clear on Monday. The border can only remain open if Northern Ireland is part of the EU Customs Union. If Britain leaves, Ulster needs a special status or an external border.
Both are unacceptable for one of the conflicting parties. That’s why the Protestant unionists reacted so indignantly to Theresa May’s recent concessions to the EU; In addition, a special arrangement arouses desires in Scotland and Wales, endangering the unity of the Kingdom.
There is no panacea for this problem. Perhaps London and Brussels will find a wording that can postpone the status issue. But even then the conflict threatens to flare up again, possibly with violence. Brexit – the dumbest political decision of the decade – can also cost lives in Northern Ireland.