The Lisbon Treaty does not change Ireland's neutrality "one iota", according to Minister for EU Affairs Dick Roche.
Speaking at a meeting of the National Forum on Europe in Co Offaly, Mr Roche said a separate Irish referendum is needed before Ireland can join a common European defence arrangement and said "it will always be a decision for the Irish people to decide these matters".
Mr Roche criticised the Sinn Féin No campaign's claim that the treaty will oblige Ireland to increase military spending, saying it "does not stand up to any objective scrutiny".
However, responding to Mr Roche's comments, Sinn Féin MEP Mary Lou McDonald said: "Interestingly Minister Roche has yet to outline to the Irish people military spending obligations within the Treaty."
Speaking last night, Mr Roche said "Irish troops cannot serve on peacekeeping missions abroad unless it is with the support of Dáil Éireann, the Irish Government and that such a peacekeeping mission is under a specific mandate of the United Nations".
However Ms McDonald said the "triple lock" system was already weakened by 2007 legislation with a change to UN "authorisation rather than a formal mandate" and she says this treaty "dispenses with the requirement for a UN mandate for military interventions."
Meanwhile, the deputy leader of the UK Independence Party, Mr David Campbell Bannerman, has withdrawn from a debate on the Lisbon Treaty tonight at Trinity College Dublin because the debate is being held in association with the National Forum on Europe.