The political progress of the last year will be lost if the impasse over decommissioning is not resolved by January, according to Mr David Ervine of the Progressive Unionist Party.
Mr Ervine was speaking at a conference entitled "Nationalism: Visions and Revisions" at the Irish Film Centre at the weekend, in which academics, politicians and film-makers viewed documentary footage drawn from the collection of the Irish Film Archive, and discussed the history of nationalism and national identity in 20th-century Ireland.
Officially opening the conference on Friday, the Taoiseach, Mr Ahern, said it was a particularly appropriate moment to debate the subject of nationalism, in the wake of the Good Friday agreement and in the light of the economic transformation of this State. Commenting on archive footage of events in the first two decades of this century, including the Easter Rising and the funeral of Michael Collins, Mr Gerry Kelly of Sinn Fein described these events as "a lost opportunity of a compromise between unionism and nationalists. Nationalists were abandoned and the unionist siege mentality was reinforced."
Speaking about last week's Remembrance Day ceremonies for the Irish dead of the first World War, Mr Kelly said it was a tragedy that the Volunteers' sacrifice had been by-passed by the tides of history. Other speakers were more critical of the ceremonies. Prof Joe Lee of University College Cork argued that the dead of the first World War were being "used to align Ireland with its new First World allies".
Prof Paul Bew of Queen's University Belfast looked at films from the 1950s, including a 1953 Irish Government-produced documentary about housing discrimination against nationalists in Fintona, Co Tyrone. He agreed patterns of discrimination in housing did exist in certain areas of Northern Ireland under the Stormont government, although not, he said, in Belfast, and that unionist leaders had not yet publicly expressed any regret over this issue.
His own view was that the process of facing up to this history would happen among unionists, but not necessarily in the way people in Dublin might like. Prof Bew described the late 1940s and 1950s as the "Golden Age of Unionism", with the existence of Northern Ireland copperfastened by the South's neutrality in the second World War and the arrival of the Welfare State in post-war Britain.
Prof Gearoid O Tuathaigh of NUI Galway, speaking on the 1930s and 1940s as the "classic age of de Valera", described de Valera's arrival in power in 1932 as a "godsend" for unionists seeking to strengthen partition, but cautioned against the current orthodoxy which viewed de Valera "across the cultural wasteland of the 1950s".
Looking at footage from the 1970s and 1980s in Northern Ireland, Ms Mary Holland of The Irish Times cautioned that "there's always a tendency at these conferences to think that these audiovisual images have an automatic authority, which is not the case".
Contrasting her experiences of covering Northern Ireland for RTE and British television, she said while there had been a greater understanding of the situation within RTE, there had also been a "deadening caution" and there had been a greater willingness in Britain to challenge the official view.
