A former Northern Ireland Secretary has told an Oireachtas committee that triggering Article 16 would be "a very aggressive and bombastic move".
Peter Hain told Joint Committee on European Union Affairs that the UK's Brexit minister David Frost's "negotiating stance...has pointed to a triggering of Article 16 and a confrontation" which is "designed to appeal to the Conservative Party's Brexit base", rather than to find a solution.
This is "a total and radical departure from the close relationship of trust" between Dublin and London, he said.
"To destroy that trust is very, very serious indeed", he added.
Michael Jay, who chairs the House of Lords European Affairs Sub-Committee on the Protocol said a 'no deal' was one possibility, but agreement could be reached by Christmas.
He added that the ECJ "is now a major issue for the British public", and features more prominently than before.
He told the committee that the "political situation in Northern Ireland during the Troubles" seemed insoluble, as the current situation does, but it was ultimately resolved by pain-staking work, and he called for "concerted efforts to build trust".
He said that the House of Lords committee was established in April, and previously appeared before the Oireachtas committee in June, when it "was in its infancy", and then gave an update on its activities since then.
Today's sitting is being jointly conducted with the Seanad Special Select Committee on the Withdrawal of the United Kingdom from the European Union and Joint Committee on the Implementation of the Good Friday Agreement.