爱尔兰边界问题因英国脱欧而再度浮现并成为脱欧谈判中的“卡脖子”问题。欧盟坚持在《脱欧协议》中加入避免爱尔兰岛出现“硬边界”的“保障条款”，增加了问题的复杂程度。英国前首相特雷莎·梅承诺维系“开放边界”，但同时将“退出单一市场和关税同盟”和“英国整体脱欧”作为底线。她无法同时实现上述三个目标，因此陷入一种“三难困境”。梅因无力解困而下台，英国脱欧变成“拖欧”。她的继任者鲍里斯·约翰逊要求废除“保障条款”，并提出以新技术为基础的“替代安排”。不管英国脱欧走向何方，爱尔兰边界问题将一直是脱欧进程中的中心议题，会持续折磨英国和欧盟。
UK’s border problem with Ireland re-emerged due to the country’s departure from the EU and has become a major sticking point in Brexit negotiations. The EU insisted putting a “backstop” mechanism into the Withdrawal Agreement as an “insurance policy” to ensure no hard border on the island of Ireland，which complicated the Irish border problem. While Theresa May promised to endorse an open border，she was also determined to “exit the single market and customs union” and uphold “whole UK Brexit”. As these cannot be realized at the same time，May was caught in a “trilemma”. Failing to resolve the Irish trilemma led to May’s downfall and a delay in the Brexit process. Boris Johnson，her successor，asked the Irish border backstop to be removed and claimed that “alternative arrangements” based on new technology would alleviate the need for an Irish border. Foreseeably，no matter what form of Brexit goes ahead，the UK and EU will be continuously afflicted by the Irish border problem.
