The leaders of Northern Ireland, Scotland, and Wales are set to hold an unprecedented meeting on Monday, aiming to push for the breakup of the United Kingdom.

John Swinney, leader of the Scottish National Party and the first minister of Scotland; Rhun ap Iorwerth, leader of the Welsh independence party Plaid Cymru and first minister of Wales; and Michelle O’Neill, leader of Sinn Féin and first minister of Northern Ireland, are all slated to meet in Cardiff, the capital of Wales, the Telegraph reported. At the meeting, the three are expected to sign a joint declaration demanding the right to hold independence referendums, a move intended to kickstart the ultimate dissolution of the U.K.