Why is the Irish border a problem?
Over the three decades of sectarian strife known as the Troubles, the Irish Republican Army battled the British Army and pro-British paramilitaries from Northern Ireland in a guerrilla conflict that left some 3,600 dead. The border bristled with military watchtowers and checkpoints until the 1998 Good Friday Accord brought peace. Both sides fear that if border controls were to be reinstituted, tensions would resurface and lead to violence. One way to avoid a “hard border” is for Northern Ireland to be included in the EU customs union, which ensures that EU member states all charge the same import duties to non-EU countries. But that arrangement would require