The Taoiseach and the British Prime Minister have asked Gen John de Chastelain to produce a formula which would enable the shadow executive and the North-South bodies to be set up by the end of the month.
In a lengthy telephone call between Mr Ahern and Mr Blair last Monday, the two leaders decided to refer the decommissioning impasse to the chairman of the International Commission for resolution.
They accepted that the two governments had failed to find a formula to surmount Mr David Trimble's requirement that some decommissioning should take place before the Northern executive could be established in shadow form, according to sources.
Mr Ahern and Mr Blair also determined that they would stick rigidly to the terms of the Belfast Agreement. The letter of the agreement does not require a gesture on decommissioning before the establishment of the shadow executive.
A hint that the focus will now be placed on the independent Decommissioning Commission to break the impasse came from Mr Ahern yesterday following a "realistic and constructive" meeting with a Sinn Fein delegation, headed by Mr Martin McGuinness.
"I am certainly reassured that the negotiations and the honouring of the [Belfast] agreement, which Martin McGuinness is involved in with Gen de Chastelain will prove to be exactly as it should be under the agreement," Mr Ahern said.
The meeting with Sinn Fein in Government Buildings lasted for 2 1/2 hours, much longer than expected. Mr Ahern had an hourlong private meeting with Mr McGuinness, Sinn Fein's representative to the International Commission, unaccompanied by officials.
After the meeting, Mr Ahern said he believed "Gen de Chastelain, as the agreement had foreseen, is the resolution of this particular issue".
Accepting that there was an impasse at the moment, Mr McGuinness said it would take the best efforts of all those who were in favour of the agreement, including Mr Trimble, to ensure that they moved on decisively to implement the agreement.
