An additional Brexit agreement to reduce checks on food and animals moving between the UK and EU should be the "direction of travel" in resolving the Northern Ireland issue, the Taoiseach has said.
Speaking at a press conference after a meeting of the British-Irish Council Irish leader Micheál Martin said statements by the US that such a treaty would not affect the UK's chances of landing a transatlantic trade deal raised the "potential for progress".
The US commitment was part of an intervention by Joe Biden at the G7 summit in Cornwall attempting to cool the Northern Ireland border issue and stave off a looming trade war between the UK and EU.
"I think it's a significant intervention, a significant point rather, to make because I understand the importance for the United Kingdom government in terms of its capacity to do trade deals in the post-Brexit world," Mr Martin said.
"From our perspective, we believe that the mechanisms exist within the trade and cooperation agreement and within the withdrawal agreement and the protocol to facilitate a working out of these issues – and there are issues to be refined and resolved, we acknowledge that."
Mr Martin said he had spoken to Boris Johnson and Michael Gove about the issue and added: "I do believe that the SPS [sanitary and phytosanitary] is certainly the direction of travel that we should pursue as constructively as we possibly can.
"And I think if the US is saying that certainly arriving at an SPS agreement doesn't in any way negatively impact on the potential of the US-UK trade deal, then I think that definitely offers up potential for progress here."
The EU has said it is open to a Swiss-style veterinary agreement, which would align the UK to EU rules on food, plant and environmental standards.
This would remove inspections for food being moved into Northern Ireland and reduce bureaucracy for trade across the Irish Sea and see the EU ease controls.
But Boris Johnson has preciously said such "dynamic alignment" would not be compatible with his vision of Brexit and there are concerns in Whitehall that closely aligning to EU rules could limit the the UK's ability to do trade deal with other countries like the US.
Mr Martin had previously highlighted the comments by US charge d'affaires Yael Lampert, made at an earlier meeting with UK Brexit chief Lord Frost in London.
The British Irish Council meeting in Fermanagh, Northern Ireland, was the last for Arlene Foster, the Northern Irish first minister, who has been ousted by her DUP colleagues.
Ms Foster burst into song at the press conference, reciting Frank Sinatra's "That's life" as she was asked about her experience at her last major meeting in office.
"I'm very pleased that everyone is here," she said, breaking into song: "That's life, that's what all the people say, you're riding high in April, you're down in May. Is that enough?"
The singing prompted Ms Foster's Sinn Fein deputy First Minister Michelle O'Neill to say: "Now we know what Arlene's next move is." Ms Foster replied: "Yes, The Masked Singer."
The Council was attended by the heads of government of Ireland, Scotland, Wales, the Isle of Mann, Jersey, and Guernsey. Michael Gove represented the UK government while Boris Johnson was at the G7. The UK prime minister has not attended the annual meeting in recent years, instead sending deputies and ministers.