The Irish government has said the post-Brexit Northern Ireland protocol is not going to be scrapped, despite calls from the DUP for it to be replaced.
A row is growing over the measure to avoid a hard border on the island of Ireland now the UK has left the European Union.
Boris Johnson has warned he is ready to override elements of the Brexit divorce settlement relating to Northern Ireland to prevent a trade barrier developing in the Irish Sea, given the disruption reported by some businesses.
Stormont First Minister Arlene Foster, leader of the DUP, says the protocol is "fundamentally flawed" and that a plan by the UK government to extend grace periods on trade changes is just a sticking plaster solution.
After pressure from the DUP to scrap the protocol, Ireland's foreign minister Simon Coveney said: "We need to be truthful with everybody - the protocol is not going to be scrapped."
He said ministers wanted to be helpful and flexibilities were possible but the problems were a consequence of the UK's Brexit negotiating stance, adding in an interview with BBC Radio Ulster: "There is not going to be very dramatic change."
But Ms Foster responded: "He is completely tone deaf to the concerns of unionism and he claimed to support the Belfast Agreement but the balance in the Belfast Agreement does not seem to matter.
"Just carry on regardless of the fact that there is not one unionist politician in Northern Ireland that supports the protocol, but what about it, we will just continue on."
She added: "We were told for years that majoritarianism did not work in Northern Ireland but it appears that majoritarianism is back and if we do not like it we just have to suck it up."
The issue was inflamed over the weekend when the EU temporarily triggered a controversial part of the protocol - Article 16.
That allows Brussels or the UK to act unilaterally to avoid serious "economic, societal or environmental difficulties", and came amid coronavirus vaccine supply struggles on the continent.
In a bid to smooth over relations, Cabinet Office minister Michael Gove and EU Commission Vice President Maros Sefcovic held talks on Wednesday afternoon.
A joint statement released by the pair said they "reiterated their full commitment to the Good Friday Agreement, and to the proper implementation of the protocol" and agreed to meet again next week in London.
But Mr Johnson said he would not be afraid to trigger Article 16 if needed, telling the Commons: "We will do everything we need to do, whether legislatively or indeed by invoking Article 16 of the protocol to ensure there is no barrier down the Irish Sea."
Physical inspections on goods entering Northern Ireland from Great Britain, which are required under the protocol, have been suspended amid threats and intimidation of staff.
Police have insisted there is no evidence that loyalist paramilitaries are involved in the campaign, instead blaming disgruntled individuals and small groups.