Northern Ireland's "extraordinary position" in the post-Brexit political landscape means it "risks finding itself caught between a rock and a hard place", according to a new report by an academic think tank.
Boris Johnson's Withdrawal Agreement had placed Northern Ireland "not only with the EU but also within the UK internal market" - but that does not mean it will be "enjoying a 'best of both worlds' scenario".
The warning comes as it was announced that the First and deputy First Minister will chair a new Stormont sub-committee on Brexit.
Writing in The UK in a Changing Europe report, Dr Katy Hayward of Queen's University, Belfast, suggested that this is because "it will remain, in effect, part of the EU's single market for goods and also de facto part of the EU's customs territory", regardless of being nominally in the UK's.
Dr Hayward suggests that "movement of goods across the Irish Sea will be directly affected by the negotiations that the UK and the EU are about to begin".
"This means potential friction within the UK internal market and additional costs for NI businesses," she adds.
Dr Hayward added that it is not yet known if Northern Ireland will benefit from being part of the UK's free trade agreements, or part of the EU's free trade agreements.
"And, on top of this, of course, Northern Ireland will have to navigate what all its parties agree to be the negative impacts of Brexit, including restricted access to labour, especially low skilled EU workers, and friction in the movement of services across the island of Ireland," she writes.
All that, combined with a tight timetable for the transition period, "plus the scale of decisions to be made by the UK-EU Joint Committee that will uniquely impact on Northern Ireland, the scale of the governance and policy challenge is evident".
The Brexit deal means that four years after the end of transition period, MLAs will vote on whether to continue to be aligned to EU rules.
Dr Hayward, a Reader in Sociology at Queen's School of Social Sciences, Education and Social Work, noted that "given the nature of politics here, this debate will almost inevitably be framed less as a policy or economic matter than as a constitutional and identity one".
She also noted how Brexit has increasingly polarised opinion over the question of Irish unity, with growing number of both unionists and nationalists thinking leaving the EU makes it more likely.
But she warned that "there's increasing polarisation in terms of how people view the prospect. In other words, Brexit has made something that people will disagree about profoundly (i.e. Irish unity) increasingly likely and increasingly consequential".
She concludes: "Northern Ireland will be affected in perpetuity and irrevocably by the UK's withdrawal from the EU - in its relationship with Ireland and with Great Britain. Whether this is for good or ill will in many respects depend on what happens over the course of the coming 11 months."
Meanwhile, speaking during First Minister's Questions at Stormont yesterday, Arlene Foster said the Executive had approved the establishment of a sub-committee on Brexit issues.
Members of the committee, which will meet for the first time today, include Economy Minister Diane Dodds, Finance Minister Conor Murphy, Agriculture Minister Edwin Poots, Justice Minister Naomi Long and Health Minister Robin Swann.
Mrs Foster said other ministers can be invited to attend "should items of particular interest to their portfolio be discussed".
"In summary, the committee will support the Executive by providing a forum for collective discussion and consideration of the implications of the EU exit on Northern Ireland in relation to influencing negotiations," she said. "It will also agree Northern Ireland policy positions on devolved responsibilities for consideration in decision-making by the UK Government and joint committee as well as developing proposals to maximise our influence at any opportunities arising from the Withdrawal Agreement, including the Northern Ireland protocol. It will also commission an assessment of the impact of the institutions and on relations north/south and east/west."
Mrs Foster said the first meeting of the sub-committee is expected to be held today "and I am confident that the wide-ranging membership of this sub-committee will allow us to consider Brexit in a holistic way".