Editorial: 'Brexit negotiations require cool heads'
As the Brexit endgame approaches, things are becoming fraught, and this seems to be especially so for those on the fringes of negotiations - the DUP and the hardline Tory Brexiteers.
In writing to the DUP leadership, Theresa May undoubtedly thought she was heading off any potential trouble from that quarter in the wake of her Cabinet discussions this week. Instead she has confused matters more than they already were and in the process, upset Arlene Foster.
It was known from earlier last week that what was likely to go to the British Cabinet was a proposal for a backstop encompassing the entirety of the UK, but with some additional custom measures for Northern Ireland to ensure alignment with EU standards. That did not frighten the unionists and would effectively mean no hard border between north and south.
The difficulty arises from the British insistence that there needs to be a built-in review process in the backstop - something which neither the Irish Government nor the EU objects to in principle. But the rest of the EU do insist that the review cannot lead to the backstop having a finite existence without being replaced by something equally acceptable, or the British having a unilateral right to abandon the backstop. Even in the event of no deal, it would still have to be part of the "divorce" agreement.
Mrs May concedes that including this in the final agreement might appear to allow for the possibility of customs restrictions between Northern Ireland and the rest of the UK - the dreaded border down the Irish Sea - but insists she would never allow this to actually come into force.
However, she has worried Mrs Foster, who says the letter raises alarm bells for "those of us who value the integrity of our precious union and for those who want a proper Brexit for the whole of the UK".
On another front, Mrs May will have to fight those in her Cabinet and party who are insisting the backstop can only be temporary so that Britain will not be tied to EU rules indefinitely.
They are quite bloody-minded in their approach, as exemplified by the former Brexit Secretary, David Davis, who has suggested that if MPs reject Mrs May's proposed deal, the EU will be willing to offer a better agreement.
Compare that with the approach of Tanaiste Simon Coveney who says that even if Mrs May succeeds in getting it through her own parliament, there is no guarantee that the deal will get final approval in Brussels, and you can see that in what should be the final days of negotiation after two and a half years, the matter is far from settled.
And as we get closer to the end, the Taoiseach may come under gentle pressure, either to concede some ground on the backstop, or to play ball on tax harmonisation to ensure continued solidarity from the rest of our EU partners. He will only get through what is immediately ahead with a cool head and a strong resolve.