The issue of the future of Northern Ireland is important because the UK is included in the UN Charter as a permanent member of the UN Security Council [UNSC] under the name “United Kingdom of Great Britain and Northern Ireland”; should that change as a result of the merger of the island of Ireland, there will be three permanent members of UNSC sitting under names different from those listed in the Charter: the UK itself, the USSR and the Republic of China.
Westminster appears reconciled to the eventual separation of Northern Ireland from the UK, and merger with the Republic of Ireland. Even the Conservative Party, whose full title is “Conservative and Unionist Party” is of the same mind.
The Troubles, lasting from the late 1960’s to the late 1990’s show that the terror campaign by the Provisional IRA worked. After each major attack, more concessions were forthcoming from London.
Foreign, especially US, pressure has also worked, and has been applied mainly in favour of the Catholics seeking merger with the Republic of Ireland. This has been especially true of Presidents of Irish extraction, Protestant or Catholic. Biden has raised this to an entirely new level.