The Ulster Unionist leader, Mr David Trimble, has said his party is ready to "jump together" with Sinn Fein to tackle simultaneously the arms issue and forming a Northern executive.
"If we believe people are committed to the process, and are prepared to do what I understand that to mean, then of course we are ready. But jumping together means you are satisfying our requirement of no guns, no government."
Speaking after his party met the former US senator and talks chairman, Mr George Mitchell, who has returned to facilitate the current review negotiations, Mr Trimble said questions had been raised about republicans' commitment to the process.
The UUP delegation presented Mr Mitchell with a report on whether the republican movement was committed to the process in the wake of the killing of Mr Charles Bennett and the uncovering of a Florida-based gun running operation in June.
The report contained "some material which he is going to reflect on", said Mr Trimble.
He repeated his claim that the UUP could not now treat Sinn Fein as a normal political party within the process while question marks remained about its commitment to exclusively peaceful and democratic means.
"We cannot, if we were to meet Mr Adams, behave as if the importation of weapons, and the killings and the shootings hadn't happened. They raise questions, so it cannot be business as usual.
"He and his movement now need to do something to establish whether they are committed to this process in good faith or not. If they are not committed, it clearly has implications for all of us. It doesn't mean that the process has collapsed but it has implications for all of us."
Mr Trimble accused the deputy SDLP leader, Mr Seamus Mallon, of sitting on the fence and questioned the party's handling of the process. "Well I notice that the SDLP, and I'm sorry to say, Seamus, seem to like to adopt this lofty position of apportioning blame to one side and then to the other side without actually mentioning themselves.
"If the truth be told, Mr Mallon's lofty position is in fact the fence and it's not a dignified position for him to continue to sit on it," added Mr Trimble.
The leader of the Democratic Unionist Party, the Rev Ian Paisley, said the DUP was attending only because it had received assurances that the first round of meetings had nothing to do with the review. "There'll be straight speech and no socialising with the senator," he added.
Dr Paisley said his party was not going back on its mandate from the unionist majority to get Sinn Fein out of the government of Northern Ireland, not into it.
"The logic of our position is to wreck anything that is going to bring out surrender to Dublin, put the IRA into talks, let the IRA prisoners out and let them keep their guns and blackmail the people of Ulster," he said.