As of last night the nature of the apparent agreement between Boris Johnson and Leo Varadkar was unclear.
The sense of satisfaction on the part of the Taoiseach on Thursday suggested a move towards his demands on customs arrangements.
If so Northern Ireland will end up with regulatory and customs checks in the Irish Sea. It is speculated that the province will technically stay in UK customs, but with some EU tariffs applied.
How did unionists reach this extraordinary situation?
Newspapers are the first draft of history, and via them and other media we already have a good idea as to how we are at this point. But soon academics will study it all in detail.
A key moment was when major business organisations endorsed the backstop and failed to speak up for unfettered Northern Ireland access to the vast internal UK market.
That consensus among business leaders was seized upon by Dublin, the EU, nationalist parties, pro Europe parties, remain MPs in Westminster, academics and the press.
Again and again, DUP politicians were grilled on the fact that they were at odds with such sentiment.
Almost no major business group, and very few economists, issued so much as a statement warning people against a trade barrier between Northern Ireland and Great Britain.
Lots of them said they wanted no barriers in any direction, north-south or east-west. But they gave weight to a backstop that, in event of no agreed UK-EU trade relationship, placed greater store by protecting north-south over east-west.
Most people agree that disrupting something as sensitive as the former is undesirable. But disrupting the latter is of far greater economic consequence given volumes.
Theresa May tried to avoid an Irish Sea border by making the backstop UK wide but even then it was full of NI specific elements such as the ludicrous ban on CCTV at the land border (which polls show only a tiny majority of nationalists strongly oppose). Some unionists foolishly agreed the land frontier must be seamless, instead of urging London to retain a right to at least cameras at the frontier.
The worst aspect of the backstop, which had no break clause, was the way that it kept Great Britain in a customs union and NI in the EU customs union, setting the scene for the former one day quitting such constraint, which NI would never be allowed to do.
The problem of the UK staying in customs union with the EU became apparent to me weeks after the 2017 backstop when the constitutional expert Vernon Bognador explained why such an arrangement is a nonsense. I realised that Middle England would not accept it long term.
We are lucky Boris Johnson has brought forward an inevitable customs showdown. A tariff border on the island of Ireland is completely unacceptable to nationalists, and a tariff border in the Irish Sea is unacceptable to unionists, but if a crisis on the issue had arisen after the backstop, it might have been too late to do anything.
But near universal business support for the backstop, cited ad nauseam in Dublin and Brussels, added to relentless pressure on the DUP to agree Irish Sea checks – which it did last week for standards of goods.
Above all, the support for the backstop of the Ulster Farmers Union, traditionally thought of as a grouping that had many unionist farmers, was cited against the DUP.
I have done broadcast interviews in the Republic of Ireland in which I have been grilled on the UFU stance, as if it rendered unionist opposition to the backstop absurd.
After the DUP agreed to the Boris Johnson plan for regulatory checks in the Irish Sea but customs divergence on the island of Ireland, Simon Coveney listed a long list of people who opposed the idea, including Simon Hamilton, in his new Belfast Chamber role, and Ivor Ferguson of UFU, whom Mr Coveney described as “a unionist”.
The only party who supported the plan, he mockingly added, was the DUP. This misleadingly bracketed TUV, UUP and other unionist opposition alongside pro backstop voices, when in fact such critics thought the DUP had gone too far towards the EU position (as opposed to not far enough).
I have not detected unease among the UFU at the way their backstop stance was seized upon by people who want Irish unity.
The UFU deserves scrutiny because it did not take a stance in the Brexit referendum. I reported a Leave event at which Ian Paisley Junior MP expressed frustration at their failure to come off the fence.
Yet I covered pro EU rallies at which other business leaders, such as Glyn Roberts of Retail NI, were key Remain voices. It is consistent for him to take the position he now does, of support for the backstop and opposition to the Boris plan.
It is perfectly reasonable for the UFU to oppose trade barriers in any direction, but if so why did they not come out against Brexit?
Legions of farmers voted to quit the EU. Presumably none of them thought Northern Ireland would not only stay in EU trade structures, but be subject to trade barriers with the rest of the UK.
I realise the UFU says its members have varied views on Brexit and that it thinks it has taken nuanced position, but it must know that politicians and the media emphasise its pro backstop stance.
Last week Mr Ferguson of UFU welcomed the all-island regulatory aspects of the Boris proposals.
Then he said: “Equally important is a commitment from the government to protect our standing in the UK’s internal market. We need concrete guarantees that access to the UK market will not be affected.”
But it is too late for that.
Access to the UK internal market most assuredly will be affected.
Ireland and Brussels insisted on such, and were able to cite business and UFU to support their demand.
• Ben Lowry (@BenLowry2) is News Letter deputy editor