Ms Truss said it would be up to the Northern Ireland Executive to decide if officials in the province should stop inspections on goods if ordered to do so by DUP agricultural minister Edwin Poots.
First minister Paul Givan said on Thursday that his DUP colleague Mr Poots would order a stop to the checks – a move branded a stunt by Sinn Fein and other parties on the executive at Stormont.
Sinn Fein deputy first minister Michelle O’Neill claimed the proposal would expose the DUP to “public ridicule”, and said civil servants would be obliged to defy any order from Mr Poots as such a direction would be unlawful.
Asked if Boris Johnson’s government would intervene, Ms Truss told the Belfast Telegraph it was a “matter for the [Northern Ireland] executive” to decide upon.
The dispute centres on whether Mr Poots requires the authority of the wider executive to conduct the checks and inspections on goods arriving from Great Britain necessitated by the Northern Ireland protocol agreed between the UK and the EU.
Claiming that recent court rulings have clarified that such authority is required, Mr Poots tried to secure the approval of the executive by asking for it to be voted on at a meeting on Thursday.
However, Sinn Fein used its own veto to prevent the issue from even getting on the agenda in the first place.
Mr Poots now claims that – in the absence of wider executive backing – he does not have the legal authority to continue the Brexit checks. It is unclear when he will formally announce that he has directed a halt to them.
But Mr Givan made clear the DUP intends to stop inspections. “Edwin Poots is going to act … That is something that the DUP have said that we were going to do, and we are going to do that.”
If protocol checks were to stop, it would put the UK government at odds with its obligations under the terms of the Brexit withdrawal agreement.
In such circumstances, the government could use its authority to direct that the checks resume.
However, that could place it in an uncomfortable position politically, given Ms Truss is currently involved in intensive negotiations with Brussels in a bid to significantly reduce the number of checks required under the protocol.
The DUP has targeted 21 February as a fresh deadline for Ms Truss to deliver a solution to protocol problems.
The foreign secretary told the Belfast Telegraph she was hopeful both sides would find a “sweet spot” in negotiations next month.
The prime minister risked heightening the row once more on Wednesday when he accused the bloc of implement the protocol in an “insane” and petty way.
EU’s former chief Brexit negotiator Michel Barnier has said Mr Johnson and his team “know exactly what they signed up for … they are the ones who negotiated”.
Mr Barnier told Politico that Mr Johnson must stop the theatrics and reach a deal on the protocol. “The British government must adopt a pragmatic attitude, without ideology” in order to “de-dramatize” the current tension.
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