The Good Friday Agreement's UN treaty status means that any compromise of the rigorous impartiality it demands of the Government could be legally challenged
Fighting by ballot box.
Violent dissident republicanism is still making its presence felt.
McGuinness attends the unveiling of a portrait of the Queen in 2016.
From handshakes to football matches, the late deputy first minister understood that little gestures go a long way.
McGuinness has died, aged 66.
The former deputy first minister was once a feared IRA sniper but became a central figure in the move towards peace.
Irish Prime Minister Enda Kenny in March.
AP Photo/Geert Vanden Wijngaert
The Irish prime minister is in Washington for the annual shamrock photo op. But, with Trump in the White House, even usually placid U.S.-Irish relations are a bit dodgy.
An October 2016 peace rally in Bogota, just before the final accords were signed with the FARC guerillas.
What can Colombia can learn from other nations' transitions, both successful and unsuccessful, from war to peace?
Still awaiting justice.
Niall Carson/PA Archive
Political disagreements are hampering those still looking for justice.
It's the first time the 'Green and White Army' and the 'Boys in Green' have competed together in a football tournament – and it's actually going rather well.
In it together: David Cameron and Enda Kenny.
The Northern Ireland peace process will not implode on a Brexit, but the EU has done a lot to help it along.
The Good Friday settlement has kept the peace, but the system is plagued by built-in instability.
It has been revealed that the Provisional IRA – the paramilitary group that fought for Northern Ireland to become separate from the UK – still exists, despite the IRA agreeing to disband in 2005. An independent…