Taoiseach Bertie Ahern has warned against "paralysis" in the peace process as the 10th anniversary of the Downing Street Declaration approaches.
The Fianna Fail leader was speaking at the annual commemoration of Liam Lynch, the anti-treaty leader whose death in 1923 marked the end of the civil war.
He said truly honouring the memory of the Co Limerick man meant being "persuaders for the cause of democratic order and political means as the only way forward".
"It is a message none of us should need reminding of," he said.
"We have in our time borne witness to our own wretched conflict that has cost well over 3,000 lives and caused colossal damage and disturbance to the lives of many more people.
"It has been in human terms one of the most costly history lessons, one that we should have been able to steer clear of or, at any rate, cut short."
However, the Taoiseach said the 10 years since the signing of the Downing Street Declaration had seen an "enormous amount of progress".
"While we are now in sight of the finishing line, we have to make certain that we do not falter in the final stretch," he said.
"Eleven months after the democratic institutions in Northern Ireland were
suspended, there is a danger of paralysis. We cannot allow that to happen."
Mr Ahern said political leaders within both nationalism and unionism were now approaching "definitive moments of transition", with the stakes raised by the shadow of an election.
Unionists of all persuasions needed to confront the reality that "devolved government can only be constructed and maintained on the basis of inclusion".
Republicans also had to "fully embrace the reality that inclusion in government is only sustainable on the basis of a democratic mandate alone and that all vestiges of paramilitarism must be consigned to the past".
"I believe that most political leaders – even if some will not admit it publicly – understand those realities and know what has to be done to resolve the issues," Mr Ahern said.
"Last May we were almost there. The fact that we were not able to achieve finality at that time, while disappointing and frustrating, has not deterred us from trying to make progress to get back on track."
The Taoiseach repeated that the process must not be allowed to become "hostage to internal turbulence and paralysis".
"Working with the British government, we are determined that the process will not succumb to any such paralysis and that inclusive political engagement will continue to be the engine of progress on this island," he said.
