Dublin and London had been fairly tight since December 1993 and the Downing Street Declaration—until yesterday morning. The Times led with 'Irish want sea border with UK after Brexit'. The DUP's Sir Jeffrey Donaldson rushed breathlessly on to the Today programme to say there was 'no way' his party would accept it.
The notion isn't new. The idea is that the customs and immigration checks move away from the land border, and are done on ports or planes reaching either island. It pours cold seawater on Downing Street's preferred idea that a 'frictionless border' can just rely on nifty cameras. 'We do not want to pretend ... we can solve the problems of the border on the island of Ireland through technical solutions like cameras and pre-registration and so on. That is not going to work,' Ireland's foreign minister told EU colleagues.
From Dublin's perspective, it puts the wind up Arlene Foster, which is always fun. But Ireland's preferred approach—shifting customs controls to seaports and airports—is politically toxic to unionists, who have a bit of a trump card in Westminster just now.
No deal with the EU would, more than likely, mean a hard border. But likelier either than this or a sea border would be a transition deal, an arrangement sought by Hammond and Davis and which even Gove and Fox are coming around to. But it is patently impossible to determine the shape of customs arrangements at the border without first determining what trade and immigration relationship the UK and EU will have after Brexit.
More importantly, we are witnessing a move away from a quarter century of tight teamwork between the UK and Ireland. It is an alliance forged in the peace process which culminated in the Queen's 2011 state visit to Dublin, with a green frock and a few words of Irish. Since Brexit, relations across the Irish Sea have cooled so much you could skate to Wicklow.
Domestic politics is becoming international here. Ireland has a rockstar Taoiseach: Leo Varadkar, an Irish version of Justin Trudeau, except gayer, more Indian, a doctor, and probably more fun down the pub. Then there is the more heavyweight foreign minister: Simon Coveney, a former defence minister and MEP who last month came within an inch of beating Leo Varadkar to the top job.
And it's not good politics right now, either at home or in Europe, to hug London too tight. Opposition leader Micheál Martin showed that opposing Brexit and Trump is a powerful vote winner in Ireland. Varadkar and Coveney, whose Fine Gael party leads a minority government, are unlikely to ignore the lesson. 'Their attitude has hardened,' said an official in Whitehall.
Between the push for a sea border and the next round of Stormont talks in autumn, Dublin and London now seem to be sailing further apart in diplomacy than they ever have in a quarter century.