Last night’s spat between the Foreign Office and the Treasury was hardly reassuring for Unionists. If you missed it, a Treasury amendment proposed a change to customs regulations where ‘UK’ was replaced with ‘Great Britain’.

What’s so bad about that, you might ask. The answer is that it would have codified the carving-out of Northern Ireland as a separate legal entity. This is something that the protocol establishes: Northern Ireland continues to follow EU customs rules while Great Britain is able to diverge. But this breaking off of Northern Ireland is something the government was supposed to be trying to prevent.

Sure enough, the amendment was pulled and Liz Truss has apparently ordered an investigation into how it got so far without ‘proper political scrutiny’. Delayed action is better than no action, of course. But this event is not going to do anything for the government’s credibility. What’s more, the signs are that ministers are now edging away from triggering Article 16, which would suspend the protocol and restart negotiation.

This is perfectly defensible, at least on a narrow view of the circumstances. Russia’s invasion of Ukraine has completely changed the international situation, and this would be an inopportune time to pick what could be an extremely long and bitter fight with the European Union. The problem is the bigger picture. To Unionists, Boris Johnson is starting to resemble the grand old Duke of York, marching his troops to the top of this hill before marching them back down again. Late last year, the government seemed to be teeing up to trigger Article 16. Then Westminster sources said they’d need to act if there hadn’t been a breakthrough by the end of February.

Given that context, sceptical observers could be forgiven for having their doubts that Truss was really going to trigger it this time – even before the Treasury gave the impression that they had mentally written off Northern Ireland and are itching to tidy up the law accordingly.

But the politics of Northern Ireland aren’t going to hit pause just because it suits London and Brussels. The lack of a resolution means that the protocol is going to dominate the upcoming Stormont elections in May, at least on the Unionist side.

This has several downsides. First, by denying the Democratic Unionists something they can tout as a win, it increases the likelihood of the Unionist vote fracturing and Sinn Fein emerging as the largest party – a development that could well see the Assembly collapse, again. Having stuck by the government and got their fingers burnt, the DUP may then be pushed into a tougher stance against a sea border. That means they’ll become less likely to work with Westminster, either to find a solution or to get a collapsed Stormont back on its feet.

There is a view that London is supposed to oversee Northern Ireland in a strict spirit of Olympian detachment. But this is to read far too much into the post-1998 commitment to avoid a discriminatory statelet like the one that grew up under the old parliament of Northern Ireland before 1972.

In fact, the government needs to command the confidence of Unionists, too many of whom currently feel that nobody is in their corner – all while Dublin and Brussels stand up for nationalist interests. Much of the siege mentality so often exhibited by Northern Irish Unionists can be put down to this dynamic. It is an outlook that in the long run helps nobody, least of all themselves.

Article 16 is not a magic bullet; it is not simply the case that Truss could pull the lever and all would be well. She and Johnson would need a comprehensive plan for navigating both the inevitable legal progress and the EU’s threatened response. Losing that contest would be deeply damaging to Northern Ireland’s position in the United Kingdom.

But in the absence of such action, Westminster needs to take much more care to avoid needlessly squandering Unionist goodwill. And with events in Ukraine so much of the Foreign Secretary’s time, she cannot afford to be running around putting out fires set by the Treasury.