Senator George Mitchell will disclose details of the format of his review at a press conference at Stormont today.
He is expected to begin meeting the political parties individually either later in the afternoon or tomorrow.
The Ulster Unionists will ask Mr Mitchell to judge the commitment to the Belfast Agreement by Sinn Fein and the fringe loyalist parties following recent paramilitary violence.
The UUP will be keen to focus on recent alleged breaches of the Provisional IRA ceasefire which, it will argue, underline the need for decommissioning. By contrast, Sinn Fein's contribution will centre on the failure to set up the executive in July.
The party will argue that the UUP has not met its obligations under the Belfast Agreement. It will insist on the need for immediate movement on policing, the criminal justice system, and the implementation of the "equality agenda".