UK Prime Minister Rishi Sunak yesterday hailed his deal on post-Brexit trading arrangements for Northern Ireland as a "decisive breakthrough".
Many Conservative MPs, including those who supported Brexit, gave their backing to the agreement.
And the DUP, whose support will be key to restoring power-sharing in Northern Ireland, said there had been "significant progress".
But the party warned that "key issues of concern" remain.
DUP leader Sir Jeffrey Donaldson said his party would now study the legal text, before reaching a decision on whether to support the deal.
The party has boycotted the devolved government until its concerns over the Northern Ireland Protocol are resolved and some Tory MPs have said they will only support an agreement if it has the backing of the DUP.
Examine details
Sinn Fein, which is the largest party in the Northern Ireland Assembly, welcomed the deal, although it said it still needed to examine the details.
The party's vice-president, Michelle O'Neill, repeated her call for the DUP to return to devolved government, adding: "We always said that, with pragmatism, solutions could be found."
After months of negotiation and speculation surrounding a possible deal, it was finally unveiled during a day of carefully choreographed events.
The BBC says word began to emerge from inside government in the afternoon that an agreement on an issue which has vexed four prime ministers had finally been done.
Mr Sunak said the new deal "delivers smooth-flowing trade within the whole United Kingdom, protects Northern Ireland's place in our union and safeguards sovereignty for the people of Northern Ireland".
Under the agreement:
- Goods from Britain destined for Northern Ireland will travel through a new "green lane", with a separate "red lane" for goods at risk of moving on to the EU.
- Products coming into Northern Ireland through the green lane will see checks and paperwork significantly reduced, while red lane goods will still be subject to normal checks.
- A "Stormont brake" allows the Northern Ireland Assembly to raise an objection to "significantly different" EU rules which would apply in Northern Ireland.
- UK VAT and excise rules will apply to Northern Ireland for alcoholic drinks for immediate consumption and immovable goods such as heat pumps. Previously EU VAT rules could be applied in Northern Ireland.