A resolution has been introduced in the US Congress opposing the return of a hard border on the island of Ireland.
Irish-American Congressman Brendan Boyle is behind the move.
He said that now was the time for the US Congress to make it clear that it stands in strong opposition to a hard border.
After introducing the resolution in the House of Representatives, Congressman Boyle said: "One of the great foreign policy achievements of the 20th century was the Good Friday Agreement.
"It eliminated the hard border that then existed between Northern Ireland and the rest of Ireland. Now Brexit threatens this."
Congressman Boyle warned that a hard border would end the free flow of people between Northern Ireland and the Republic of Ireland, something which he said had proved fundamental to promoting peace and unity.
Earlier, he tweeted his response to the latest Brexit developments in the British parliament writing: "After agreeing to the Irish backstop, Theresa May’s government has now reneged on it. Why would anyone negotiate with her now?"
Latest developments reinforce need for 'workable' backstop - Varadkar
British MPs vote to replace backstop with 'alternative arrangements'
Brexit - What happens next?
Backstop is not up for renegotiation - Govt and EU