MercoPress. South Atlantic News Agency

The Good Friday Agreement that helped end The Troubles

The deal set out rules on how Northern Ireland's special power-sharing legislature, which demands participation from the largest parties on both sides of the divide, would function.

The 1998 deal was the culmination of years of talks which helped end decades of violence known as the Troubles. The conflict pitted largely Protestant unionists who preferred to stay part of the UK against largely Catholic republicans, who wanted to be united with the Republic of Ireland in the south.

The years of conflict often spilled out into mainland Britain, with terrorist attacks striking London, and even one against then Prime Minister Mararet Thatcher..

Chaired by the US in the later stages, the deal settled the UK and Irish governments' respective claims to Northern Ireland. Under the agreement, both sides effectively pledged to respect the outcome of any decision made by the Northern Irish at a possible future referendum. The consent of voters in the south would also be required to change the status quo.

The deal also set out rules on how Northern Ireland's special power-sharing legislature, which demands participation from the largest parties on both sides of the divide, would function.

And most importantly, it negotiated the permanent cease-fire and disarmament of the militant Provision Irish Republican Army (IRA) and some other comparable paramilitaries. Some more radical groups rejected the accord, splintered from their original groups and continued to fight.

However the shadow of the Troubles has returned to Northern Ireland since Brexit made alterations to the conditions upon which the 1998 deal was based.

Despite the doubt Brexit cast on Northern Ireland's trade ties with the rest of the EU, including the Republic of Ireland, these ultimately emerged from the process almost unchanged. Northern Ireland's trade ties with the rest of the UK, however, became subject to some new restrictions as a trade-off.

Britain and the EU recently struck a revised deal that aims to reduce some of the complaints on the Northern Irish side, generally from unionists favoring unbridled trade with the rest of the UK.

With the UK no longer part of the European Union, its trade agreements with the bloc were upended. The Republic of Ireland remains an EU member state.

“While it is time to reflect on the solid progress we have made together, we must also recommit to redoubling our efforts on the promise made in 1998 and the agreements that followed,” Sunak said in a statement marking the agreement's anniversary.

In February, the UK and the EU reached a new post Brexit deal for Northern Ireland.

Dubbed the “Windsor Framework,” the plan aims to scrap some checks on goods crossing from the rest of the UK into Northern Ireland, and give Northern Irish lawmakers greater say over future EU-related rules.

However, it has yet to garner the needed endorsement at home from the pro-UK Democratic Unionist Party (DUP), with tensions about the deal still high in Belfast. The party said Biden's visit would not pressure it to change course.

Biden, who quite often refers to his Irish ancestry, plans to use the trip to reconnect with his roots. He is due to spend three days in the Republic of Ireland and address the parliament in Dublin.

The US president is scheduled to meet distant cousins in County Louth on Wednesday. He also plans to visit the western county of Mayo, where his great-great-grandfather grew up, and address thousands of residents there.

Biden is also a symbol of the historic importance of the ties between Ireland and the US.

Like Biden's ancestors, millions of Irish people crossed the Atlantic in the late 19th century and early 20th century, escaping the famine at home and seeking a better future.