Depleted shelves are seen in a Sainsbury's supermarker at the Forestside shopping centre in Belfast, Monday, Jan. 11, 2021. The U.K.s biggest supermarket chains warned Wednesday, Jan. 13 that food supplies in Northern Ireland face disruption because of new checks imposed by Britains departure from the European Union. A trade deal that took effect Jan. 1 allows Britain and the EU to trade in goods without quotas or tariffs. But that is a far cry from the seamless, hassle-free trade the U.K. enjoyed while it was part of the EU’s single market. Northern Ireland remains closely tied to the bloc’s economy under the Brexit divorce terms in order to protect its open border with EU member Ireland.