STORY: The UK and the European Union struck a deal on Monday to potentially end one of the biggest remaining disputes after Brexit.
The friction stemmed from rules over trade for Northern Ireland...a difficult and controversial aspect of the UK's split from Europe... both for the EU and Northern Ireland's lawmakers.
But on Monday - UK leader Rishi Sunak hailed a new chapter in relations with Brussels, calling the deal a 'decisive breakthrough.'
"Today's agreement delivers smooth flowing trade within the whole of the United Kingdom, protects Northern Ireland's place in our union and safeguards sovereignty for the people of Northern Ireland.''
The so-called 'Windsor framework' seeks to resolve the tensions caused by the Northern Ireland protocol.
That agreement effectively created a customs border after Brexit in the sea between Britain and Northern Ireland.
Sunak said the framework would remove "any sense of a border" between Britain and its province,
while European Commission President Ursula von der Leyen said it provided a long-lasting solution:
"The new Windsor framework respects and protects our respective markets and our respective legitimate interests. And most importantly, it protects the very hard-earned peace gains of the Belfast Good Friday Agreement for the people of Northern Ireland and across the island of Ireland."
The deal still needs to be approved by the UK parliament.
Britain's main opposition Labour party has thrown its support behind the agreement,
but its success likely hinges on the approval the Democratic Unionist Party and Eurosceptics within Sunak's own party.
The DUP is currently boycotting Northern Ireland's power-sharing arrangements,
which were central to the 1998 peace deal known as the Good Friday Agreement.
U.S. President Joe Biden, who often speaks with pride of his Irish roots, has welcomed the deal,
calling it an "essential step" to ensuring peace is preserved.
A sentiment echoed by U.S. National Security Spokesman, John Kirby:
"I mean, we're grateful that the two sides were able to come up with this Windsor framework, as they call it, this this agreement in keeping with the Northern Ireland protocols, which we believe that this will help improve the prosperity of both the EU and the UK and will open up all kinds of now avenues for trade."
U.S. officials had previously warned that any action which endangered the peace agreement could harm the prospects of a U.S.-UK trade deal.