British Prime Minister David Cameron has set June 23 as the date for a referendum to decide whether the United Kingdom will remain in the European Union. If Britain chooses to exit the EU (the so-called Brexit option), the ramifications will be felt across Europe, but perhaps nowhere as sharply and dangerously as Northern Ireland.
For more than 40 years, the EU has provided the benign and neutral political framework that has helped foster and preserve the peace between Protestant unionists and Catholic nationalists in Northern Ireland. But now it is English nationalists - an increasingly strident faction of Cameron’s Conservative Party and the vociferous right-wing UK Independence Party - who threaten to undo that progress.
Their movement taps into some of the same populist sentiments that motivate supporters of Marine Le Pen in France and Donald Trump in the United States: They are tired of austerity policies, angry about low wages or lack of jobs and are fearful of losing the jobs they do have to immigrants and refugees in an open-border Europe.
The stakes are high. A vote to leave the EU might destroy the United Kingdom: Scotland might revisit secession from the UK so that it could stay part of Europe. Where would that leave Northern Ireland?
In Northern Ireland, the Brexit debate is opening up old sectarian divisions. The Irish nationalist parties, the Social Democratic and Labour Party and Sinn Fein, want to remain in the EU; pro-British unionists mostly want to leave. The latter have always been suspicious of Europe diluting their British identity, including enforcing legal changes around social and moral matters. Unionist farmers and businesses, however, may vote to remain in Europe because they enjoy massive subsidies from Brussels, equal to more than 4% of Northern Ireland’s output and more than 80% of its farm revenue.
The Northern Ireland economy is still shaky. Being detached from Europe would not only mean losing those subsidies, but also its attractiveness to global companies looking to invest in a low-tax corner of the European Union.
John Hume, who shared the 1998 Nobel Peace Prize for his role as architect of the Good Friday agreement, brilliantly saw that a shared European identity could reduce the hostility and suspicion between Catholic nationalists and Protestant unionists.
Instead of a zero-sum debate over spoils within Northern Ireland, the two sides would together fight for more subsidies from Europe and investment from abroad. It worked. For years, former political enemies made common cause, in Hume’s words, “spilling their sweat and not their blood”.
EU membership likewise improved relations between the Republic of Ireland and Britain. The constant contact between government officials at weekly EU meetings created common bonds and reduced the sense of Ireland being a small neighbour of Britain, an island behind an island.
If Britain votes to leave, however, the border between Northern Ireland and Ireland would become the EU’s external border. How long before British police roadblocks are rolled out to keep Middle Eastern refugees from coming in via Ireland, which would presumably become part of border-free Europe? (To date, Ireland has opted out of the Schengen Agreement.) The Irish government has made clear its interest in having Britain stay in Europe, but only UK voters will decide, based on local issues.
The larger danger of course is that Brexit could upset the delicate balance in Northern Ireland. Disappointed nationalists might seek some form of a united Ireland, triggering a negative reaction by unionists. Whatever way one looks at it, reopening these identity issues gives extremists issues to exploit and risks destabilising the region.
It’s worth recalling that the momentum for building a “United States of Europe” after World War II was propelled in large part by a determination to avoid further devastating violence.
The hope was that being part of Europe would tame nationalist fervour and make everyone more secure, prosperous and tolerant. That stayed true for the initial years, but recently Europe has failed important tests such as the widespread unemployment crisis, the Russian challenge to Ukraine and the debt crisis in Greece.
The EU may be too large and diverse to progress any further toward a “United States of Europe”. It is very hard for 28 European states with different languages, histories, economies and domestic pressures to agree on what will solve their problems.
Member states already are losing trust in the collective European border-free policy, with some closing their shared borders in response to the refugee crisis.
The Brexit debate is causing people across Europe to ask: What does Europe mean for them? Recently, the Czech government hinted that it too would consider leaving if Britain did.
It may well be that EU leaders will have to delay their push for an “ever closer union” until Europe delivers on its original mission of more security, jobs and prosperity. But, regardless of how Britain votes on June 23, one thing is sure: Those with any interest in peace in Northern Ireland will be hoping that the British stick with Europe.

- Ted Smyth, a communications and public affairs strategist based in New York, is a former Irish diplomat.