The border between Northern Island, part of the United Kingdom, and the Republic of Ireland, as well as the debate on how to uphold the Belfast Agreement and keep the free flow of movement across the frontier without violating the UK constitutional integrity is one of the crucial issues in the Brexit negotiations.
"They discussed the two key outstanding issues in the negotiations: the future economic partnership and the Northern Ireland backstop. The Prime Minister underlined the need to… find a solution to the Northern Ireland border and maintain the constitutional integrity of the UK… The Prime Minister confirmed that the government would also bring forward further proposals on the Northern Ireland backstop," the spokesperson said.
The United Kingdom voted to leave the European Union in a referendum in June 2016 and is expected to do so by late March 2019.