Edward BurkeAssistant professor of International Relations at the University of Nottingham

Brexit may not yet destroy the Northern Ireland peace process, but it has certainly weakened its fundamental pillars. First, Brexit has added much poison to already difficult relations between Northern Ireland’s two leading parties, the Democratic Unionist Party (DUP) and Sinn Féin. Northern Ireland’s unionists largely voted to leave the EU, whereas nationalist voters—including those for Sinn Féin—chose to remain. Brexit paints both parties into their respective corners. Unionists will not accept any significant divergence from the rest of the UK. Sinn Féin, in turn, are threatened by the clear realization that their advocacy of the Good Friday Agreement—that it would lead to an irreversible increase in all-island political, economic, and social ties—no longer applies.

There is also an increased absence of trust between Dublin and London, since long-standing convergence on Europe and Northern Ireland has now fractured. A hard border, including the introduction of infrastructure to police a new customs border, threatens to become a running sore on the island of Ireland. It will become a target for terrorists and criminals alike, with the increased risk of political escalation as border communities protest against this unwanted barrier.

Tony ConnellyEurope editor at RTÉ

Brexit is certainly putting a strain on the peace process. Anglo-Irish relations are as bad as they have been in decades, there are low levels of trust between Dublin and the DUP, and Brexit is further polarizing the main unionist and nationalist parties in Northern Ireland.

The very issue on which Brexit might flounder—the Irish border—is the subject of a political and legal tug of war between hardline Brexiters and the DUP on one side, and the Irish government and the EU taskforce on Article 50 negotiations on the other. To make matters worse, the constructive ambiguity of the peace process, which allows tribal adversaries to feel they have won enough, is no match for the hard legal obligations of single market and customs union rules.

Theresa May’s dependence on the DUP has resurrected fears among nationalists of a conservative and unionist monolith, redolent of the early part of the twentieth century, when a different European conflict was brewing. All told, trust is low and tension is high.

All sides periodically profess a determination to protect the Good Friday Agreement. Yet the structural weight of Brexit’s contradictions could erode the peace process further, if destruction is too strong a word.

Federico FabbriniProfessor of European Law at Dublin City University (DCU) and Director of the DCU Brexit Institute

Brexit is a major challenge to the Northern Ireland peace process due to the threat of a hard border between Ireland and Northern Ireland. However, the Good Friday (or Belfast) Agreement has not been destroyed, and its achievements can be preserved.

Both the UK and the EU are fully aware of the delicacy of the issue—and the resolution of the Irish question has been a key item in the Brexit negotiations. The EU institutions and the UK government have repeatedly proclaimed their commitment to there being no border between the Republic and the North as a condition to preserve the peace process.

The December 2017 Brexit deal identified several options to maintain a seamless border on the island of Ireland, and the European Commission’s draft withdrawal agreement, published in February, translated that pledge into law. The UK prime minister discarded the EU-proposed solution to the Irish border question but confirmed in her March 2 speech her intention to solve the problem.

So the political will to preserve the peace process remains and legal ways are available to achieve that. Yet a close association of the UK to the EU would ease things, and the negotiations on the future EU-UK relations will be crucial in this regard.

Ashley FoxMember of the European Parliament and leader of the British Conservatives in the European Parliament

On March 2, the prime minister could not have been clearer. She pledged no hard border between Northern Ireland and the Republic post-Brexit and that nothing would be done to threaten the progress made in bringing peace to the province.

Mrs. May proposed a package of potential measures, including implementing EU customs checks on goods entering the UK, trusted trader schemes, and the use of technology. She also reiterated her December 2018 commitment that, in the absence of other solutions, the UK would maintain alignment with those rules of the internal market and customs union that protect the 1998 Good Friday Agreement.

Ultimately, it is hoped the answer will lie in a comprehensive UK-EU trade deal. Until the outcome of those talks is known, there can be no definitive solution.

In contrast, Brussels’ only suggestion is that Northern Ireland remains “part of the customs territory of the EU.” Not only does this contradict what was agreed in December, but Brussels also knows that no UK prime minister could accept this.

The EU must lay aside its desire to keep the UK bound to its rules and regulations and engage constructively. Brexit is only a threat to the Northern Ireland peace process if the EU, through its inflexibility, recklessly chooses to make it so.

Peter KellnerVisiting scholar at Carnegie Europe

No, Brexit is not destroying the Northern Ireland peace process. If anything, the opposite is nearer the truth: the Northern Ireland peace process could end up destroying Brexit.

The detailed issues concerning the border between Northern Ireland and the Irish Republic—the only land border between the United Kingdom and the rest of the European Union—are complex; but the bottom line is simple. Theresa May’s government has three objectives that are mutually incompatible: no customs union with the EU after Brexit; no hard border on the island of Ireland; and no East-West trading barriers between Northern Ireland and the rest of the UK. Britain’s government can have any two of these, but not all three.

Mrs. May hopes that technology will come to her rescue and allow checks on the Irish border that won’t involve any barriers, border posts, or checkpoints. Nobody outside the British government thinks this is possible. More to the point, if Mrs. May asked the House of Commons to approve a form of Brexit that required any form of Irish border, most MPs are likely to reject it. The UK would end up either negotiating a customs agreement that keeps the Irish border fully open, which would nullify much of the point of Brexit, or unleashing a political process that leads to Brexit being abandoned altogether.

Denis MacShaneFormer UK minister for Europe

Brexit has fused with the Irish question, which devoured British politics for more than 100 years.

In 1998, it seemed with the Good Friday Agreement that Ireland could finally put its demons in a sealed box called “history.” In the United Kingdom’s territory in north-east Ireland, the two communities could maintain their allegiance and identity—one British, the other Irish. An all-Ireland economy was created within the EU, just as there is an all-Ireland rugby team.

However, the interpretation put upon by Brexit by hardline Northern Ireland Protestant politicians (who have always disliked any compromise with Dublin) and by anti-Irish English Tories has raised old demons. The hardliners refuse to contemplate all of Ireland staying in the EU Customs Union, which would allow the borderless all-Ireland economy to function as is does today. Instead, they want a border with checkpoints and customs controls reinstalled.

The former UK prime minister Sir John Major has warned that “the memory of that border is so toxic that no one who knew it in the past wishes to see it return—in any form—in the future… The fear is that the border becomes a target— an outlet for unionist or nationalist fringes that wish to provoke trouble.”

Mrs. May’s majority depends on the votes of extreme Northern Irish MPs. So far, she has indicated she would rather sacrifice the peace process than face down her supporters. Yeats might have been describing Brexit and Nothern Ireland when he wrote: “The best lack all conviction, while the worst are full of passionate intensity.”

Mary C. MurphyLecturer in the Department of Government and Politics at University College Cork

The European Commission’s draft withdrawal agreement on the terms of the UK’s departure from the EU has heightened political tensions in Northern Ireland and has led to friction between the Republic of Ireland and Britain. Nationalists in Northern Ireland and the Irish government support the proposed legal text, while the British government and unionists are utterly opposed to a formula that is perceived to place a border between Northern Ireland and the rest of the UK.

Brexit has evoked acute political sensitivities in Northern Ireland, and the British government faces an extraordinary dilemma in dealing with the quandary. Dependent on the DUP, the government is highly sensitive to unionist objections to any form of distinctive treatment of Northern Ireland and is also keen to protect the territorial integrity of the UK. Yet there are no alternative proposals that offer comparable protection for Northern Ireland interests.

Should Brexit produce a hard border, the prospect of serious instability in Northern Ireland is very real. At its worst, it may lead to powerful pressures for constitutional change on the island of Ireland and the attendant tensions which this will produce. A failure by the British government to contemplate challenging and difficult choices risks undermining the very thing that it and unionism seek to protect, namely the unity of the UK. The current proposals offer a means to thwart such forces by essentially maintaining the constitutional status quo in Northern Ireland. Brexit certainly has the potential to upset the Irish peace process—but it is the British response that may, or may not, seal the fate of Northern Ireland’s fragile peace.

Ben TonraDirector of the Institute for British-Irish Studies at University College Dublin

It certainly has the potential to. Brexit’s identity politics have already heightened intercommunity tensions in Northern Ireland at a time when the two key parties in the collapsed power-sharing government remain at odds. Brexit has also rocked the bilateral Irish-British relationship. Irish diplomats succeeded— and deservedly so—in placing the border issue among the key issues to be resolved as part of the EU’s initial approach to Brexit and any withdrawal agreement. There would appear to be serious annoyance in London that a) the EU would concern itself so directly in support of Ireland’s position; b) political assurances from the British side are not deemed sufficient to pass over the border issue and simply “move on” to talks on the wider EU-UK post-Brexit agenda; and c) an Irish government would insist—through the EU—on holding the British government to account over its commitment to no return to a hard Irish border.

The difficulty for both the UK and EU is that the border issue encapsulates the internal contradictions of the UK’s Brexit agenda while the security implications of a hard border remain real. Serious stakeholders—such as the NI police chief—have underlined these potential threats to a still-fragile peace. While imagination, wit, and good will may yet square the impossible circles of Brexit and an open Irish/EU-UK land border, there is no doubt that the pressures are tearing at deep and still very tender historical wounds.