Why Ireland’s Border Is Brexit’s Intractable Puzzle

The boundary between the Republic of Ireland and Northern Ireland was long the scene of tense checkpoints and violent protest. Nearly two decades after the end of a conflict that claimed 3,500 lives, the undulating border is once again caught up in a bitter division. When British and European Union leaders carry out the split -- Brexit -- that British voters ordered up, the border between Ireland’s north and south will be the only land crossing between the two jurisdictions. With both sides facing off over the fine print of their separation, Ireland’s border is proving one of the most vexing issues.

That’s one scenario -- a return of customs controls, along with the delays and costs that would entail. But since cross-border trade is worth more than 3 billion euros ($3.5 billion) a year, there’s a desire to avoid disruptions, especially given concerns that a return to checkpoints and watchtowers could endanger the region’s peace process. Both sides broadly agree that people and goods should move seamlessly back and forth. There’s a discussion about possible technical solutions, such as cameras, drones and a system for pre-clearing goods. So far though, there is no sign of an agreement.