The frontier between the Republic of Ireland and Northern Ireland remains the essential conundrum of Brexit. British Prime Minister Boris Johnson is determined to leave the European Union by Oct. 31, with or without a negotiated transition deal. But any departure must address the historically fraught Irish border, which is set to become the only land crossing between the EU and the U.K. after Brexit. Johnson has devised a plan that tries to please both British lawmakers and leaders in Brussels and Dublin. It’s not at all clear he’ll succeed.
Throughout the Brexit negotiations, the EU has insisted that only goods meeting its rigorous customs and regulatory standards will be allowed to enter the bloc once the U.K. exits. At the same time, both sides agree that the frontier should remain invisible, so that people and goods can easily cross back and forth. A return to checkpoints and watchtowers would bring back bad memories, more than 20 years after a peace agreement largely ended decades of violence, and could endanger the region’s fragile peace. A controversial compromise to resolve the problem sank former U.K. Prime Minister Theresa May.