Some commentators have called the agreement “Sunningdale for slow learners,” suggesting that it was nothing more than what was offered in the 1973 Sunningdale Agreement.  This claim has been criticized by political scientists such as Richard Wilford and Stefan Wolff. The first said that “he.. significant differences between them [Sunningdale and Belfast], both in terms of the content and circumstances of their negotiations, implementation and functioning`.  The agreement was formally concluded between the British and Irish governments and eight political parties in Northern Ireland, including Sinn Féin, the Ulster Unionist Party, the SDLP and the Alliance Party. The DUP was the only major political faction that opposed it. The IRA renewed its ceasefire on the 20s. This paved the way for Sinn Féin`s participation in the inter-party talks that had begun under Mitchell`s presidency. However, the question of dismantling remained and the British and Irish governments tried to give the problem instead of letting it derail again. As a result, hardliner Ian Paisley`s Democratic Unionist Party (DUP) left the talks and never returned. The DUP refused to make concessions to Northern Ireland`s constitutional position or negotiate with Sinn Féin, which it considered terrorist.
Although deeply dissatisfied, the more moderate UUP remained in the talks. Given the DUP`s stated desire to break off talks, Mitchell later wrote in his memoirs that their decision to leave had actually helped the process of reaching a deal. .