"Don't even annoy my head with that," says Mitchel Mc Laughlin. Irritated, he's responding to the criticism, made by unionists and many nationalists, that a relatively small organisation such as the IRA is showing breathtaking arrogance by sacrificing the Belfast Agreement over a few arms.
We are in the Sinn Fein chairman's spanking new office in the Rathmore shopping centre, high up on the Creggan in Derry City. The local Sinn Fein press officer, Dominic Doherty, is sitting in, apparently to ensure everything is pukka. "Astonishing arrogance - you say that to me against the background of what the British army has done on this republican community. We are talking about right up to the present day. Look at the way the Bloody Sunday tribunal is being handled. Look at the way the evidence is being systematically destroyed in front of our eyes."
The Taoiseach, Mr Ahern, in common with other politicians such as David Ervine of the Progressive Unionist Party, recently suggested that a possible way of circling the decommissioning obstruction would be for the IRA to state that its war is over.
"Do you think the war is over?" McLaughlin says with some passion. "Go out there and take a wee look at that lookout tower. Look at that military installation and tell me do you think that the war is over, because it's not over." If the war is not over, he adds, how can the IRA declare that it is over? The IRA guns are silent, though, and that is the basis on which politicians should be trying to resurrect themselves from the current totally depressed state of politics.
Listening to Mitchel McLaughlin's arguments and analysis, there appears to be little prospect of any progress in the near future. In the earlier days of the peace process, when unionists were warily and very gradually finding themselves on platforms with Sinn Fein, it was McLaughlin who was often sent out to argue the republican line.
Unlike some of his colleagues in Sinn Fein, he did not have the smell of cordite about him. He was jokingly referred to in the assembly by unionists as the "conscientious objector" because he was seen as an exclusively political animal.
When Martin McGuinness and Gerry Adams travelled through the 1990s on the long peace process path, they were enthusiastically joined by McLaughlin on what was at times a shaky venture. He supported the processes and worked hard to sell them to the rank and file.
Now, though, he is in assertive mood. There is a potentially dangerous political vacuum but he won't accept republicans are to blame. He criticises The Irish Times editorial line on decommissioning. He says this reporter is ill-informed on some issues.
Even fellow Derry man Eamon McCann earns his rebuke for suggesting elsewhere that if the IRA could not move on arms, Sinn Fein should resign from the executive and go into effective opposition. "How many votes has Eamon McCann got? It is a nonsense. We are not having it. No way. We represent and we will defend the rights of our electorate all the way down the line.
"The deal is that if we have enough votes, and we have, we will be involved in the executive and we will not surrender that to anybody, and we are certainly not going to surrender that on an issue such as decommissioning."
Neither does McLaughlin accept the unionist claim that republicanism has betrayed the Belfast Agreement. It was Peter Mandelson, he says, with the connivance of David Trimble, who created this crisis. No, republicans never conveyed the impression that if David Trimble moved on government, the IRA would move on guns.
So, what were Hillsborough in April 1999, the Way Forward enterprise last July, and the Mitchell review last November all about? It was about making politics work, not guns, says Mitchel McLaughlin. "Republicans have never broken any commitments," he says.
Among a considerable portion of the body politic, there was at the very least a strong perception, and even an expectation, that some movement on IRA arms would follow the creation of an executive.
Peter Mandelson said decommissioning would happen, President Clinton indicated that if it didn't, unionists could walk away, Bertie Ahern said the progress achieved would "fall apart" if there was no decommissioning by May. If there was such a perception, republicans did not create it, McLaughlin says, they stood by the agreement.
He argues that Sinn Fein has strictly adhered to its commitment to use its influence to persuade the IRA to decommission. When it's put to him that Sinn Fein helped to create the expectation of movement on arms when it accepted that decommissioning was an "essential part of the agreement", he emphatically says, "No." The line is that decommissioning is an "essential part of the peace process". He says journalists who do not see this distinction are ill-informed.
This, however, confounds one of the three principles to which Sinn Fein signed up in the Way Forward document last July, that all parties accept there should be "decommissioning of all paramilitary arms by May 2000".
Irrespective, he says what is in the Belfast Agreement must be the arbiter of all disputes and "decommissioning is not an essential part of the agreement".
Politicians now seem to be scrambling in the dark. There is a sense they are going through the motions but privately believing that the position is generally hopeless. He presents a bleak analysis but says all is not yet lost.
"The IRA called a ceasefire and honoured it. That was what they were asked to do, to provide space for the politicians. What was bolted on to that was a demand that they surrender their guns. They are not prepared to do that. We have to create a set of political conditions in which that will happen organically," he says.
"Organically" appears to mean every aspect of the Belfast Agreement in place and then maybe some movement on arms.
"We have to create the conditions in which the British army are out of the equation, where the RUC guns are out of the equation, where the licensed weapons are strenuously and rigorously reviewed to see who actually needs a gun, and then deal with the substance of IRA guns and loyalist guns in that same political context. We still believe we can achieve a situation where all of the guns, not just the IRA guns, are removed from the equation. We think the process is unstoppable. "At the end of the day, you know how this peace process will work - when you get to the point when the IRA can trust the British government to keep its word, and the British government can trust the IRA to keep its word.
"You see, for the rest of us, all we can do is build the political structures around that. That is the essential bridge of trust that has to be constructed."
The way Mitchel McLaughlin tells it, it will be a long time before such mutual trust is established. "What we are doing, the near miraculous thing that we are managing, is to keep the peace.
"We are managing to keep the space in which politicians will eventually get their heads around this problem. To try to short-circuit that [through the call for decommissioning] has not served this process."