Britain's exit from the European Union raises the spectre of a new hard border between the province, which is part of Britain
As counting begins after Northern Ireland's snap elections, the youthful new leader of the nationalist Sinn Fein party in the province warned about the effects of Brexit on both sides of the Irish border.
"I think Brexit is catastrophic for the island of Ireland," Michelle O'Neill told AFP in an interview in the village of Toome in her constituency.
O'Neill said it "undermined" the Good Friday Agreement, a 1998 accord that ended three decades of conflict in Northern Ireland that cost around 3,500 lives.
"The Good Friday Agreement has been underpinned by European legislation, in particular human rights legislation, so Brexit is going to have serious implications for guaranteeing those rights."
Britain's exit from the European Union raises the spectre of a new hard border between the province, which is part of Britain, and the Republic of Ireland, which remains an EU member.
In the June referendum Northern Ireland voted to stay in the EU but the result in Britain as a whole was for Brexit.
The prospect of border checks has revived memories of a time when the border was patrolled by British soldiers, who frequently became targets for militants, and criss-crossed by smugglers.
At a time when Northern Ireland should be spelling out its demands for upcoming Brexit negotiations with Brussels it has been roiled by political bickering.
'Direct rule failed'
Elections were called in January after long-simmering tensions boiled over between Catholic, Irish Republican socialists Sinn Fein and the Democratic Unionist Party, which is Protestant, conservative and pro-British in its outlook.
Sinn Fein's deputy first minister Martin McGuinness quit in January, saying he could no longer work with first minister Arlene Foster, the DUP leader, blaming her for a botched green heating scheme that she had instigated when economy minister.
The former Irish Republican Army (IRA) commander's departure paved the way for 40-year-old O'Neill, herself the daughter of a former IRA prisoner, to become the party's leader after serving as a government minister for five years.
O'Neill's uncle is a former IRA fundraiser while her cousin, Tony Doris, was one of three IRA members shot dead by British special forces in 1991.
The political deadlock is threatening to re-open old wounds and O'Neill signalled a possible way out.
"We're up for going back into government but only on the basis of equality, respect and integrity," O'Neill said.
"We cannot go into government with Arlene Foster as First or Deputy First Minister while there is a shadow hanging over her, but that doesn't mean we can't find a way forward."
Sinn Fein and the DUP are expected once again to be the two main parties following Thursday's vote, and therefore bound to form a power-sharing executive, with the winner electing the province's First Minister and the second party nominating its Deputy First Minister.
However, the DUP are expected to nominate Foster, threatening deadlock and possible direct rule from London if it cannot be broken within three weeks.
"We are not planning for direct rule -- direct rule failed the people here and it will again," warned O'Neill.