JOE Biden has described the Windsor Framework as an "essential step" towards protecting peace as he heaped praise on the EU and UK government for securing the revised protocol deal.
In a speech at Ulster University that celebrated the progress made since the Good Friday Agreement, the US president said Brexit had created "complex challenges" for Northern Ireland.
He said he had encouraged both sides to "address the issues in a way that served Northern Ireland's best interest".
"I deeply appreciate the personal leadership of Prime Minister Sunak and European Commissioner Von der Leyen to reach an agreement," he told an invited audience at the Belfast city centre venue.
"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."
Mr Biden stressed the potential economic opportunities offered by February's revised protocol deal.
"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," he said.
The president voiced hope that the power-sharing institutions could be restored soon,
"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," he 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."
Praising the cross-party response to the shooting earlier this year of senior PSNI officer John Caldwell, Mr Biden said "standing for peace and rejecting political violence" was something that should unite political rivals.
"The attack was a hard reminder there will always be those who seek to destroy, rather than rebuild," he said.
"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."
British Prime Minister Rishi Sunak, who met the president in Belfast ahead of his Ulster University engagement, said the visit was a reminder of the US contribution to the peace process.
First minister designate Michelle O'Neill said the president had sent a "clear message to the DUP" about the restoration of the Stormont institutions.
The Sinn Féin deputy leader and her counterparts separately held brief meetings with Mr Biden.
"I think he sent a very clear message that everything that has been achieved over the past 25 years is something to be celebrated, but he very much was future focused, he was looking forward to the next 25 years, it was about the hope and the opportunity, but I think his message was clear, we need peace, we need stability and we need prosperity, those things all go hand in hand," she said.
"I think his message was very much on the right note."
But DUP leader Sir Jeffrey Donaldson, whose party continues to boycott power-sharing over its concerns around the protocol, said the presidential visit did not change the "political dynamic".
He described the president's speech as "measured" but stressed that devolution would not return until the British government took further steps to address his party's concerns over post-Brexit trading arrangements.
"I'll be meeting my team over the next few days and we'll be going back to the government," the Lagan Valley MP said.
"We believe the government needs to go further in terms of protecting Northern Ireland's place within the United Kingdom and our ability to trade within the UK internal market and that's what needs to happen now to enable us to move towards the restoration of the political institutions, we need the government to deliver what they've said they will do, which is to protect our place in the United Kingdom."
Alliance leader Naomi Long said Mr Biden's message was "positive and balanced".
"He was also well aware of the challenges facing the restoration of the assembly and executive, but was keen to see that happen as soon as possible," the East Belfast MLA said.
“When one of the largest economies in the world spends its time, effort and money showcasing us, we need to grasp that opportunity with both hands."
Ulster Unionist leader Doug Beattie said the president's visit was an "indication of the scale of opportunity that stands to be grasped for our people".
"Whilst today there was rightly reflection on the importance of the Belfast Agreement in securing the peace we have enjoyed for 25 years now, there was also a welcome focus on prosperity," he said.
"The next 25 years must be about delivering opportunities and prosperity for all our people."
SDLP leader Colum Eastwood said, during his meeting with the president, Mr Biden was "very clear" that the White House administration and US businesses were "ready to come and invest".
"I reminded him that John Hume used to say the best peace process was a job, and of course he agreed with that," he said.
"We've seen great strides over the last 25 years but I can tell you from outside of Belfast, places like Derry, there is a lot further to go yet and we really need investment."
Dr Francis Costello, a Belfast-based Irish-American business consultant and academic, said the president's visit highlighted the need to address educational underachievement.
``There must be at long last a serious commitment to reaching young school leavers especially in the loyalist community to get the education and skills needed to help play an active part in growing that economy in order to feel some ownership in society," he said.
"Twelve years after the Purvis/Shirlow Report on the high-level loyalist youth educational underachievement, the problem is even worse – opening new university glass towers in central Belfast will ring hollow if such a large section of the community remains a dependent and inactive underclass unable to uplift themselves by education."
