Brexit disrupts supply chains
The Good Friday Agreement of 1998 is largely credited with ending what had become a low-level civil war. One of its key stipulations was keeping the land border open between the Republic of Ireland and Northern Ireland — a development made possible in no small part because of the UK and the Republic of Ireland both being EU members in the single market and the customs union at the time.
Brexit negotiators aimed to protect the Good Friday Agreement. They drafted the Northern Ireland Protocol, which kept it in the EU's customs union and enabled the border to remain open.