Former Senator George Mitchell has said he is going to Belfast to chair the review of the peace process impasse "with a great deal of personal reluctance".
When he was asked by the two prime ministers to take on this task, "I very much did not want to go back", he said, , but "I did not feel I could say no".
Mr Mitchell, who was being interviewed on National Public Radio, also said the unionists "do not believe that decommissioning is going to occur" and feared if they entered the Executive without decommissioning, the two governments would not allow it to be dissolved at a later time even though no arms were handed over.
Mr Mitchell, who was briefed this week in New York by British and Irish officials, said he has made it clear to both governments that the review beginning next week would be limited. "On this occasion I have made clear to the prime ministers and the political parties that I am not able to take part in an open-ended process." The previous negotiations took two years, he said. "I cannot do that."
He said this would be a "tightly focused review, not a renegotiation of the agreement". It would be limited to the two subjects of decommissioning and the formation of the Executive and "limited in time". He has not yet established a time limit. He refused to give any estimate on how long the review will last, pointing out that the situation in Northern Ireland has "deteriorated in the past few weeks" and that he does not know yet if "all the parties will come to meet me".
He believed there could yet be a legal challenge to the decision by the Secretary of State, Dr Mo Mowlam, that there has not been a significant breach of the IRA ceasefire. He also expected continued opposition to her decision.
Asked about the opposing viewpoints on decommissioning and the formation of the Executive, Senator Mitchell referred to the influence on the nationalist and republican side of "the history of British domination of Ireland which began some 800 years ago".
On the unionist side, "there is a total absence of trust" on decommissioning. They "want tangible evidence before they take the step of getting into the Executive and getting government up and running," he said. `Whatever one feels about the validity of both of those points of view one must accept them as a reality with which one must deal.
"A mistakenly-held belief can be just as deeply held as correctly held belief. I don't suggest that either is mistaken."