The whole reason for the backstop being in the Withdrawal Agreement that sets out the terms of the UK‘s divorce from the EU is that the Republic‘s border with Northern Ireland would, after Brexit, be the external border of the EU‘s single market – and therefore has to be governed by a treaty between the UK and EU, and not one between the UK and the ROI.

An official from an EU capital also questioned whether the Republic could possibly accept „a bilateralisation that would deprive it of the clout of the EU“.