Decommissioning is casting doubt over the establishment of a Northern Ireland shadow executive and, by extension, over the promised North/South Ministerial Council designed to deal with issues of common economic and administrative concern.

Strand Two of the Belfast Agreement, which deals with North/South bodies, their functions and relationships with the Northern Assembly and the Oireachtas is scheduled to be agreed by October 31st. But David Trimble, as First Minister, argues that decisions in this matter can be taken by himself and Seamus Mallon, representing Northern Ireland's transitional administration, rather than by a fully-functioning shadow executive, which would include Sinn Fein.

The Government disagrees, holding that such a work programme cannot realistically be agreed until the shape of the new shadow executive has been defined and without input from those expecting to hold ministerial office.

A similar approach was adopted some weeks ago by the Northern Ireland Office in a draft paper on North/South bodies in which it envisaged "the shadow North/South ministerial council, as part of its work programme, identifying and agreeing . . . areas for co-operation".

But Mr Trimble is holding firm. And while the agreement envisages the involvement of a shadow executive, it doesn't specifically prescribe it. Just as with prior decommissioning and membership of a shadow executive, it seems no explicit requirement exists.

As part of this skirmishing, Mr Trimble wants decisions on the nature and extent of North/South bodies taken in the first week of October, before he embarks on a 10-day trip to the United States. The Government has pencilled in the second and third weeks of October for negotiations, moving right up against the October 31st deadline.

There is another factor in play. By seeking agreement on North/South bodies in advance of the formation of a shadow executive, Mr Trimble may be in a position to limit the range and functions of such bodies. The terms of the Belfast Agreement lists 12 specific areas for North/South co-operation and implementation: agriculture, education, transport, environment, waterways, social security/social welfare, tourism, relevant EU programmes, inland fisheries, aquaculture, health and urban and rural development. It also allows for other areas "to be considered by the shadow North/South Council". But if the shadow Council does not exist, then the areas of co-operation will almost certainly be limited to those already identified.

In its draft paper, the Northern Ireland Office spoke of the need for the shadow executive "to identify and agree in consultation with the British government at least six areas for co-operation in each of the following categories: matters where existing bodies will be the appropriate mechanisms for co-operation in each separate jurisdiction; and matters where the co-operation will take place through agreed implementation bodies on a cross-border or all-island level".

Identifying areas suitable for joint action by new implementation bodies, the document listed inland waterways, tourism marketing , inland fisheries, teacher exchanges, strategic transport planning, environment protection and marine research.

New and amending legislation would be required before a formal transfer of powers to these implementing bodies could take place. The cost of the departure in each jurisdiction would be about £10 million, the document said, and decisions would have to be taken on whether budgets were to be integrated or kept separately.

So far, the Government has declined to outline its proposals. And, according to officials, it has not exchanged papers with the Northern Ireland Office. While recognising that key developments will be in areas already identified by the Agreement, other possibilities are also being examined. Work involving senior officials from the Taoiseach's Office and that of Foreign Affairs is going ahead, with the Department of Finance keeping a watching brief on possible costs. The Office of the Attorney General is also examining necessary legislative changes.

All of these elements must be in place before power is formally transferred to the Northern Ireland Assembly and to its ministerial executive next February.

But the February date is itself uncertain. It does not appear anywhere in the agreement. The two governments agreed informally during the Good Friday negotiations that time was required to allow the shadow executive prepare itself for power and to pass legislation. So next February was suggested as a starting date. But slippage could take place under a provision that states the agreement will not come into force until the governments notify one another of their satisfaction that everything is in place.

The present political skirmishing has its roots in the decommissioning issue, with Mr Trimble insisting he cannot appoint Sinn Fein to a shadow executive in advance of decommissioning and Sinn Fein insisting they have a right to be there. Ulster Unionist sources talk about an executive being formed in the pre-Christmas period, or even in early 1999. But, in spite of that, the Government still hopes the October 31st deadline for the establishment of North/South bodies - with inputs from a shadow executive - will be met.

It seems like a vain hope, given the political difficulties that have to be surmounted. But great obstacles have been overcome in the past. And, as the parties inch their way towards grudging trust and compromise, it may be that the establishment of North/South bodies, in itself, could mark a step forward.