The Taoiseach has defended his decision to meet Gerry Adams in Washington in the wake of the Sinn Féin president's exclusion from St Patrick's Day celebrations in the White House yesterday.
Mr Ahern's decision to meet Mr Adams is at odds with the attitude of the British government which is refusing to hold talks with Sinn Féin until the issue of alleged IRA criminal activity is resolved.
The Taoiseach Mr Ahern
Mr Ahern met Mr Adams on Wednesday night in advance of a White House engagement with President George W Bush and members of the family of murdered Belfast man Robert McCartney.
Speaking during an interview with RTE news today, Mr Ahern said: "The fact is that people voted for the Good Friday Agreement. The mandate that I have is the mandate of the Irish people north and south...and that's to implement the Good Friday Agreement and engage with everybody to try to do that.
But he warned republicans: "We're not going to go soft on any of the issues of the last few months".
Following yesterday's White House meeting with President George W Bush, Mr Ahern said Sinn Féin faced "total exclusion" in the United States unless the IRA disbands and ends criminality.
The British government said today that political progress in the North will be stalled until Sinn Féin deals with IRA criminality.
Speaking from Washington, Northern Secretary Paul Murphy said the ball was firmly in the court of republicans to deal with the issue once and for all.
He told the BBC Radio 4 Today programme: "To all intents and purposes we are not talking about any future negotiations or discussions until the issue of criminal activity on the part of the IRA is addressed.
"The onus is entirely on the leadership now of Sinn Féin to resolve the issue of criminality, and until that happens we have not got any hope at all of making any progress towards restoring the institutions of Government in Northern Ireland."
Mr Murphy said the visit of the McCartney sisters to the US capital over the St Patrick's Day holiday had brought IRA violence and thuggery into sharp focus.
"The fact that they have got this remarkable campaign has personalised the issue of criminal activity in a way which, here in the US, has been very well understood because people see individual human beings being affected by brutality and savagery."
The McCartney family travelled to Washington to highlight their campaign for the murderers of their brother Robert to be brought to justice.
The sisters and Mr McCartney's partner have met President George Bush and other leading US politicians while Sinn Fein president Gerry Adams has been snubbed by the political establishment in the US capital.
Mr Murphy said the reaction of Irish Americans could have a positive impact on the family's campaign back in Northern Ireland, encouraging witnesses to come forward and give evidence.
"I hope that people who have any knowledge at all of that murder can feel satisfied in the sense that everybody across the world would be behind them if they come forward with information."
Meanwhile, SDLP leader Mark Durkan has said the unwavering stand of the five sisters had moved the peace process at unprecedented speed.
"The McCartney family is very clear about what justice demands and has held strong to those demands where the two Governments have faltered," he said.
"By doing that they have moved the movement on five times in as many days."
Mr Durkan claimed that the reason the McCartney sisters' campaign to bring their brother's killers to justice had had such resonance was because the public was used to accepting compromise.
He said it was their determination to accept nothing but the truth that had spurred leading politicians, including Mr Bush and Senators John McCain, Ted Kennedy and Hillary Clinton, to speak so strongly on their behalf.