What happens with the Northern Ireland peace deal will reverberate far beyond the UK

“When your own prime minister shafts you; when he comes to this city and says there will be no border between us and Britain, and then breaks his word so easily; when your voice is being ignored – you feel abandoned, and there are consequences,” said the loyalist community leader in Belfast after another night of petrol bombs and buses being set on fire.

The man speaking to me was a former member of the Red Hand Commando who had fought during the long years of the Troubles. The violence we were witnessing was taking place in spring 2021, as tensions reignited over the Northern Ireland protocol. The prime minister accused of lying was Boris Johnson.

The protocol had been signed 15 months earlier, along with the Brexit agreement, 23 years after the Good Friday (or Belfast) Agreement had ended 30 years of bombings and shootings that had cost more than 3,500 lives. Today, the impasse over the protocol, which is intrinsically linked to the peace deal, continues, bringing with it the spectre of a return to the days of strife and unrest.

During the Brexit negotiations, both the UK and the EU agreed that preserving the Belfast Agreement was an absolute priority, and the protocol was a fundamental part of this endeavour. It was ratified by both sides and is now part of international law.

What happens to the peace deal has reverberations beyond the UK and the European Union. The US, under Bill Clinton’s presidency, played a key role in brokering it in 1998, and successive US administrations have committed to its preservation. The chances of any UK trade deal with America will disappear if the Belfast Agreement is imperilled.

Speaking at the St Patrick’s Day celebrations in Washington last year, Joe Biden emphasised the importance of what is at stake: “The Good Friday Agreement has been the foundation of peace and prosperity in Northern Ireland for nearly 25 years. It cannot change,” he said. All sides, the US president stated, “must continue to resolve challenges over the implementation of the Northern Ireland protocol”.

The protocol is essentially a trading agreement for the movement of goods across the Irish land border, in relation to which new regulations became necessary after Brexit because of the EU’s strict rules on border checks on some items coming from countries outside the union.

The border is a politically sensitive issue in Ireland, both north and south of the border, and there is real apprehension that reimposing overt border controls, with cameras and checkpoints, would encourage instability and invite attacks. Dissident armed republican and loyalist groups continue to maintain a presence in Northern Ireland, despite the years of relative calm.

The protocol agreed that the checks would take place at Northern Irish ports rather than at the land border, and that once they had been carried out, the goods concerned could then be transported to the Republic. It was also agreed that Northern Ireland would continue to adhere to European Union rules governing the standard of goods.

The unionist parties in Northern Ireland opposed the deal because, they claimed, the sea border undermined the province’s place within the United Kingdom. There has also been opposition to it from Eurosceptic MPs in Westminster, led by the European Research Group (ERG), which has continued to exert an influence well beyond its numbers on each of the Conservative governments since Brexit.

The continuing opposition of the Democratic Unionist Party (DUP) to the protocol has meant that there is currently no Northern Ireland government at Stormont. Although the party came second to Sinn Fein, which supports the protocol, in the elections six months ago, no administration can be formed without the backing of the DUP.

There is also a view among the wider loyalist community that Tory ministers from London misled them about the impact of the deal. Seven months after the signing of the protocol, Johnson, who was then prime minister, insisted during a visit to Northern Ireland that businesses would have unfettered access to markets in England, Scotland and Wales, as they had always done. “There will be no border down the Irish Sea,” he declared. “That will happen over my dead body.”

David Campbell, a spokesperson for the Loyalist Communities Council, an umbrella group that represents the Ulster Volunteer Force, Ulster Defence Association and Red Hand Commando, told me: “The view among many people in the unionist community is that the government, basically, cannot see beyond middle England. We wondered if Boris Johnson fully understands what’s at stake here.

“On the other side we have had the Irish government constantly telling the EU that there will be violence if there is a hard border; that is seen by the loyalists as using the threat of violence to bargain. That has been a dangerous tactic, and has certainly contributed to the anger among young loyalists.”

The British government has reneged on its agreement with the European Union over the protocol, which took four years to negotiate, claiming a legal entitlement to do so in order to “safeguard an essential interest”. Disagreements emanating from the deal, it held, threatened to undermine peace.

The UK wants to make unilateral changes to the checking status, bringing in a two-tier system, which would also require changes to be made to the tax regime for businesses in Northern Ireland, and would exclude the European Court of Justice from any dispute procedure, replacing it instead with an independent body. The current Northern Ireland minister, Steve Baker – an ERG member – has proposed reopening the Brexit agreement, negotiated by fellow hardliner David Frost, in order to strip the European Court of Justice of any role in the proceedings.

It is hardly likely that the EU would agree to such changes. It has taken legal action against the UK for failing to adhere to the protocol, and has stated that it is not prepared to renegotiate the main terms. But there is, Brussels acknowledged, room for simplifying rules and cutting red tape.

Negotiations on technical aspects of the protocol restarted in October for the first time since February. And, after the acrimony of the Johnson years, which continued during the brief premiership of Liz Truss, there seems to have been a general improvement in relations under Rishi Sunak.

Earlier this month, Ursula von der Leyen, the president of the European Union, said she had held “encouraging” talks with Sunak, and suggested that the two sides should be able to “find a way” on the protocol. Indeed, she said she was “very confident” that a solution would be found if the UK was willing.

Von der Leyen’s words, spoken during a visit to Dublin, were echoed by the Irish prime minister Micheal Martin, who claimed that a deal could pave the way to a “new and vital partnership” with the UK. Miguel Berger, the German ambassador to London, sees a new “openness to engage” from Downing Street under the Sunak government, and spoke of a possible “landing zone for the Northern Ireland protocol’s implementation”.

But Sunak, like Tory prime ministers before him, remains hamstrung both by his party’s Brexiteers and by the DUP in Northern Ireland. His freedom of manoeuvre is limited by those who see any compromise as an act of betrayal. The anti-EU Bruges Group tweeted this month: “Another sell out incoming? If the EU is making cautiously optimistic noises about a deal, we can be assured that whatever half-baked drivel emerges will be bad for the United Kingdom.”

Meanwhile, the threat from Northern Ireland-related terrorism remains “severe”, according to security and intelligence services. It was claimed last month that loyalists had planned an attack in the Irish Republic amid rising tensions over the protocol. The plot, thought to have been a response to Sinn Fein’s call for “joint authority” in governing the province with Dublin, was said to have been abandoned at the last minute.

The Belfast Telegraph has reported that loyalist groups the Ulster Volunteer Force and UIster Defence Association are reviewing their ceasefires, which were put in place following the Good Friday Agreement. The mood at a meeting of their leaders in County Antrim, according to the paper, was “angry and militant”. One of those present is reported to have said, “There were no hawks and doves there: everyone is a hawk now.”