Leaders of the main Scottish, Northern Irish and Welsh nationalist parties on Monday declared their right to choose whether to remain in the UK or not at a rare meeting in the Welsh capital Cardiff.

All three parties — the Scottish National Party (SNP), Plaid Cymru in Wales and the pro-Irish unity Sinn Fein — want to break away from the UK.

The meeting came just days after US President Donald Trump waded in, saying he would back a united Ireland, which Northern Ireland’s Michelle O’Neill said showed “the unity debate is very much alive”.

“Our nations have the right to self-determination. No Westminster government (the UK government) has the right to block democracy or undermine the principle that our people will decide their own future,” a memorandum of understanding stated.

SNP leader John Swinney, Rhun ap Iorwerth, leader of Plaid Cymru in Wales and Mary Lou McDonald and O’Neill, leader and deputy leader of pro-Irish unity Sinn Fein met in their capacity as party leaders, rather than as officials in their respective governments.

O’Neill is also Northern Ireland’s first minister while Iorwerth and Swinney are first ministers of their respective nations.

Announcing the agreement, Swinney said the three parties were “absolutely united by that principle of self-determination”, adding that this “lies at the heart of the agreement that we have signed today”.

“For the first time ever, people across these islands have first ministers in Scotland, in Wales and in the North of Ireland who are all committed to independence from the United Kingdom,” the memorandum of understanding said.

“The future of our nations belongs in the European Union.”

The independence parties are the biggest in both the Scottish and Welsh parliaments for the first time since devolution measures began in 1999. Sinn Fein has been the biggest party in Northern Ireland’s