Earlier this month, we wrote about how Boris Johnson’s decision to put the negotiations over Northern Ireland in the hands of Liz Truss might change the dynamic of the talks.

As a serious contender for the leadership, and thus keeping an inevitable eye on the selectorate therefore, the Foreign Secretary has more incentive than ever did Lord Frost to take a muscular line with the EU, perhaps up to and including actually triggering Article 16.

Have we now detected the first tremors of this earthquake? Media reports yesterday suggest that Truss has signalled that Westminster will not use its authority to overrule Democratic Unionist ministers if they follow through on their latest threat to suspend checks at the Irish Sea border, saying it is “a matter for the Executive”.

Whether or not this line actually holds is a separate question: commentators sceptical of the DUP’s faith in the Conservatives have pointed out that London has taken this line before, only to fold later.

But one can see how it might suit Truss to have Edwin Poots playing bad cop as she leads the talks with Maroš Šefčovič and makes upbeat noises about a deal. And the Government has played fast and loose with the Protocol before, when it repeatedly extended ‘grace periods’ in order to avoid disruption of intra-UK trade.

That doesn’t mean that suspending checks was her idea. The DUP face a very difficult election in a few months, and need to re-consolidate their position as the dominant party for Unionist voters if they’re to have any chance of edging out Sinn Féin and holding on to the merely titular, but symbolically charged, post of First Minister.

As a result, this would probably have happened regardless of who the Prime Minister had tasked with unpicking his Ulster knot.

Yet that same political ticking clock is what makes Poots’ move so high-stakes. Once he has suspended checks, it will be extremely difficult for he and his colleagues to climb down before May without offering an open goal to the Traditional Unionist Voice (TUV), which is just waiting to do to the DUP what the DUP did to the Ulster Unionists in the Noughties.

The pressure will therefore be on for Truss and Šefčovič to come to acceptable terms. Should they fail (and as I noted in a recent column, Whitehall sources are pessimistic) the question becomes what happens when the February deadline, which seems to have been unofficially set in London and has been made explicit by the DUP, comes and goes?

Which brings us back, once again, to Article 16. And it’s here that the phony war over the leadership might be making itself felt.

At the time Truss was appointed, I suggested that Johnson might have despatched her to Northern Ireland, the historic graveyard of ministerial ambitions, in order to undermine her leadership prospects:

“If Liz Truss has seen Dune, she will likely have a firm grasp of the spirit in which Boris Johnson has charged her with taking over Lord Frost’s negotiations with the European Union. The Padishah Emperor of the Known Universe sent his enemies to govern the titular planet in order to wipe them out. Prime ministers are not above sending colleagues to Northern Ireland with similar intentions.”

But this morning’s papers suggest that he has chosen instead to wield the Ulster issue against another target: Rishi Sunak.

According to the Daily Telegraph, the Chancellor has been accused by ‘allies of the Prime Minister’ of blocking plans to trigger Article 16, alleging that he is a “nominal Brexiteer”. The line is echoed by the Daily Express, which reports that Sunak wants to avoid “upsetting [the] EU”.

Johnson being Johnson, we have no real way of knowing if this is a real row, or he is simply trying to use an attack on his most obvious potential challenger to cover the exact same retreat from Article 16 he made last year.

But if Truss can’t strike a deal by February, and subsequent failure to trigger it signals to the EU that they have exhausted London’s political will on the question, there seems no way to avoid the Sea Border dominating the Stormont elections, with toxic and potentially fatal implications for Northern Ireland’s fragile constitutional settlement.

Ultimately there are only three ways out of the impasse: a land border which will offend nationalists, a sea border which offends unionists, or pretending there is no border at all, which offends the EU (although given that the grace periods produced no noticeable market distortions, would not actually hurt it). If Brussels meant what it said about putting peace in Ulster first and foremost, it would bite the bullet on option three. That still seems a long shot from here.