US President Joe Biden has expressed hopes of a return to power-sharing at Stormont as he insisted stable devolved government could deliver an economic windfall for Northern Ireland.
In a keynote address at Ulster University in Belfast, Mr Biden praised the work of the UK and European Union to strike the Windsor Framework on post-Brexit trading arrangements.
The president's visit to Northern Ireland comes on the 25th anniversary of the Good Friday Agreement that created Stormont's power-sharing institutions.
The Democratic Unionist Party, which is blocking those institutions in protest at Brexit trade barriers between Britain and Northern Ireland, has said the framework does not go far enough to address its concerns over sovereignty.
Mr Biden met with Stormont's political leaders before making the speech at the university's new campus.
Earlier, he had a 45-minute meeting with British Prime Minister Rishi Sunak at the Belfast hotel where he stayed overnight.
"As a friend, I hope it's not too presumptuous for me to say that I believe the democratic institutions established in Good Friday Agreement remain critical for the future of Northern Ireland," President Biden said.
"It's a decision for you to make, not for me to make, but it seems to me they are related. An effective devolved government that reflects the people of Northern Ireland and is accountable to them, a government that works to find ways through hard problems together, is going to draw even greater opportunity in this region.
"So, I hope the assembly and the executive will soon be restored. That's a judgement for you to make, not me, but I hope it happens, along with the institutions that facilitate north-south and east-west relations, all of which are vital pieces of the Good Friday Agreement.
"For in politics, no matter what divides us, if we look hard enough, there are always areas that's going to bring us together if we look hard enough. Standing for peace and rejecting political violence must be one of those things."
President Biden said the response of Northern Ireland's political leaders to February's shooting of PSNI Detective Chief Inspector John Caldwell in Omagh, Co Tyrone showed "the enemies of peace will not prevail".
Mr Caldwell was seriously injured in the dissident republican murder bid.
"Northern Ireland will not go back, pray God," said Mr Biden.
"The attack was a hard reminder there will always be those who seek to destroy, rather than rebuild.
"But the lesson of the Good Friday Agreement is this: at times when things seem fragile or easily broken, that is when hope and hard work are needed the most."
Mr Biden said Brexit had created "complex challenges" for Northern Ireland.
"I encouraged the leaders of the UK and the EU to address the issues in a way that served Northern Ireland's best interest," he said.
"I deeply appreciate the personal leadership of Prime Minister Sunak and European Commissioner (Ursula) von der Leyen to reach an agreement.
"The Windsor Framework addresses the practical realities of Brexit and it is an essential step to ensuring the hard-earned peace and progress of the Good Friday Agreement that they are preserved and strengthened.
"Negotiators listened to business leaders across the UK and Ireland who shared what they needed to succeed, and I believe the stability and predictability offered by this framework will encourage greater investment in Northern Ireland, significant investment in Northern Ireland."
Mr Sunak welcomed the president's visit and said it was a reminder of the US contribution to the peace process.
The British prime minister, who did not attend Mr Biden's speech, said a key focus of their earlier meeting was leveraging more economic opportunities for Northern Ireland.
"We spoke in particular about the incredible economic opportunities that are there in store for Northern Ireland and we talked about the investment potential that is there, the companies that want to invest in Northern Ireland," he said.
"I think that is incredibly exciting, it will bring growth, jobs and prosperity to Northern Ireland and I know he shares my ambition to see the institutions here back up and running, that is what people and businesses in Northern Ireland deserve."
At the outset of Joe Biden's half-day of engagements in Northern Ireland, the White House insisted the president is not anti-British.
Mr Biden, who is intensely proud of his Irish ancestry, has been criticised by senior DUP figures, with MP Sammy Wilson claiming the president "has got a record of being pro-Republican, anti-unionist, anti-British" while former first minister Baroness Foster has suggested he "hates the UK".
But the suggestion he was anti-British was rejected by Amanda Sloat, senior director for Europe at the US National Security Council, who said: "It's simply untrue - the fact that the president is going to be engaging for the third time in three months, and then again next month and then again in June, with the prime minister of the UK shows how close our cooperation is with the UK."
Mr Biden became the fourth serving US President to visit Northern Ireland when Air Force One touched down at RAF Aldergrove, a secure military facility attached to Belfast International Airport, shortly after 9pm last night.
He was greeted and welcomed to Northern Ireland by Mr Sunak.
Following this afternoon's address, President Biden left Belfast to travel to Dublin and Louth.
Read more:
Sunak greets Biden as Air Force One touches down
Packed itinerary for four-day visit of Joe Biden
Good Friday Agreement at 25 - the US view
Previous visits to Ireland by US presidents
Additional reporting Conor Macauley, AFP
