Why does Brexit matter to Connecticut? Ireland.

Recently, we joined Speaker Nancy Pelosi and a delegation of members of Congress on a congressional mission to the Europe. We were also accompanied by Richard Neal, Chairman of the Ways and Means Committee and co-chairman of the Congressional Friends of Ireland Caucus.

Our trip primarily focused on meeting with our elected counterparts and other officials across the Atlantic to discuss U.S. interests in Ireland and in the United Kingdom — the nations of England and Northern Ireland.

Given Connecticut’s many business ties to Ireland, it’s important to understand the ramifications that Brexit might have on our state.

With great uncertainty due to Brexit, as well as on the endurance of the Good Friday Agreement, our visit to England, Ireland and Northern Ireland came at a crucial time. Our message throughout the journey was clear: Any outcome of Brexit negotiations must ensure the continuation of a seamless border between Irish people in the North and South in order to preserve the spirit of the peace process that ended decades of violence.

The United States has long played a pivotal role in promoting peace in the North of Ireland. The Good Friday Agreement is the cornerstone of the peace process that led to demilitarization, the free movement of citizens between Ireland and Northern Ireland and the promotion of nonviolent political change.

Unfortunately, ongoing political differences in the British Parliament over both the withdrawal agreement from the European Union and the backstop arrangement for Northern Ireland threaten all that has been achieved since the Good Friday Agreement.

This uncertainty has been used to stoke undercurrents of mistrust and violence between the nations of the United Kingdom — an ugly trend that seemed to boil over during our visit to Derry/Londonderry on the same day that 29-year-old Lyra McKee, a brilliant and promising journalist from Northern Ireland, was killed by thuggish, self-proclaimed “nationalists” during another riot against police. This sort of senseless violence brought about by mistrust and economic uncertainty seems to be on the rise in the region, and it underscores the need to reinforce the peace-keeping arrangements and to not put them at risk with a hard Brexit.

For nearly 40 years before the peace agreement was signed, the border of Northern Ireland and the Republic of Ireland was marred by violence. We cannot let Brexit disrupt the Good Friday Agreement, not when an entire generation of Irish and North Ireland citizens have grown up knowing only peace. Any exit plan for the United Kingdom the European Union must ensure that there remains a border between the Republic of Ireland and Northern Ireland with no hard barriers.

Anything less than that would violate the Good Friday Agreement and result in violence.

During our meetings, it was clear that no one wants to return to sectarian violence. However, proponents of a clean break from the EU’s customs union (which would lead to a physical border along Northern Ireland) continue to reject the backstop arrangement that would allow a border without any physical barriers in Northern Ireland.

Many of those pressing for a “hard Brexit” do so under the presumption that a free trade agreement with the United States would help meet their post-Brexit promises. We stressed, however, that the U.S. Congress and the Ways and Means Committee will leverage its full authority over trade negotiations to ensure the architecture of the Good Friday Agreement remains intact.

When it comes to trade and economic relations between Ireland, the United Kingdom and our state of Connecticut, a threat to the endurance of these peace accords could come with serious consequences.

The Good Friday Agreement has led to unprecedented economic cooperation between our state and the United Kingdom. In 2015, the U.S. Department of Commerce organized a trade mission to Belfast including members of Congress (including Rep. Courtney), American trade representatives and 12 different Connecticut businesses, to meet and discuss potential partnerships with Northern Ireland firms like Bombardier and others in the aerospace and supply chain sectors.

That mission resulted in an eight-company delegation from Ireland and the United Kingdom travelling back across the Atlantic later that year to attend an aerospace and defense summit in Mystic, Conn. This year, firms from Northern Ireland are registered to attend Connecticut’s Space Trade Summit, taking place later this month. Their travel to our state should be relatively simple, as Ireland’s flagship airline, Aer Lingus, is now in its third year of operating non-stop flights from Dublin to Bradley International Airport.

Any disruption of the peace brought about by the Good Friday Agreement as a result of Brexit negotiations would surely threaten the positive economic developments that our region has enjoyed with Ireland and the United Kingdom for years.

The United States and United Kingdom have withstood many challenges over the years. Together we have fought to protect our shared values of peace and democracy, and we are confident our special alliance will prove instrumental in maintaining a peaceful border between the Republic of Northern Ireland and Irish Republic.

John B. Larson represents Connecticut’s 1st District in Congress. Joe Courtney represents the 2nd District.