Although the peace process initially progressed to a large extent, tensions intensified in 2001, with the intensification of sectarian conflicts, riots, political differences and the process of dismantling. Real IRA bombs on the BBC and a business district in London threatened to derail the peace process.   The Holy Cross conflict in north Belfast from June 2001 would become an important episode of sectarian conflicts. Widespread riots broke out in July and in the same month, the Ulster Freedom Fighters (UFF) withdrew from the Good Friday Agreement, while the Progressive Unionist Party (PUP) withdrew from the „current phase“ of the peace process.  On 26 July, the two extremists of the Ulster Unionist Party (UUP), David Burnside and Jeffrey Donaldson, both called for their party to withdraw support from the new Stormont assembly.-  After the British Parliament voted to leave the European Union, all parties said they wanted to avoid a hard border in Ireland. , in particular because of the historically sensitive nature of the border. Border issues were one of the three priorities negotiated in the proposed withdrawal agreement. Following the UK`s exit from the European Union on 31 January 2020, this border is also the border between the EU and a foreign country. The Brexit withdrawal agreement obliges the UK to maintain an open border in Ireland, so that (in many ways) the de facto border is the Irish Sea between the two islands. The two main political parties in the agreement were the Ulster Unionist Party (UUP), led by David Trimble, and the Social Democratic and Labour Party (SDLP), led by John Hume.
The two heads of state and government together won the Nobel Peace Prize in 1998. The other parties to the agreement were Sinn Féin, the Alliance Party and the Progressive Unionist Party. The Democratic Unionist Party (DUP), which later became the largest Unionist party, did not support the agreement. When Sinn Féin and loyalist parties entered, they left the talks because republican and loyalist paramilitary weapons had not been decommissioned. On the Republican side, the „no“ campaign seemed to focus on the purity of the republican ideal of total and absolute independence from Britain.