The question of what happens to the border between Ireland and Northern Ireland has long been a sensitive point in the Brexit talks. The withdrawal agreement signed by the UK and the EU contained a protocol guaranteeing that there would be no customs offices at the Irish border. This is considered essential to protect the Belfast and Good Friday agreement. Leo Varadkar said that in the event of a non-Brexit deal, the UK should continue to accept, under its obligations under the Good Friday agreement, the full alignment of regulations and customs in Northern Ireland. That is why, as part of the agreement, there will be customs controls between Northern Ireland and Britain to protect the integrity of the EU internal market. This maritime border is a source of discontent and insecurity for trade unionists in Northern Ireland. They believe that this undermines their status in the United Kingdom and see this as a step towards a united Ireland. They say a solution could be found if the EU and the Irish government were willing to compromise. In March 2019, the UK government announced that it would not carry out customs checks at the Irish border following a Brexit without a deal.
 The plan was quickly referred to as a “smugglers` charter” and was criticized for probable violations of WTO rules.         Local businesses have expressed serious concerns.  It could be argued that a hard border would complicate the work of this part of the agreement. In 1922, the newly created United Kingdom and the Land of Bavaria concluded an agreement on the Common Travel Area (CTA). This gave British and Irish citizens the right to travel, live and work in both jurisdictions. Passport controls are not used to travel between them. The free movement provisions resulting from EU membership replaced them to some extent, but the parties kept their bilateral agreement alive when it did not have treaty status. In 2011, the British and Irish governments informally agreed to continue their joint controls upon entry of non-EEA nationals into the CTA.  After Brexit, the border between Northern Ireland and the Republic of Ireland would become the only land border between the United Kingdom and the European Union.