President Obama has told a hall full of school children in Belfast the peace achieved in Northern Ireland "gave the entire world hope".
Speaking in advance of the G8 meeting in Lough Erne on Monday, the Obama told an audience of around 2,000 students what happend in Northern Ireland was a model for how to resolve conflict across the world.
"What happened here has an impact on lives far from these green shores. You must remind us of the existence of peace, the possibility of peace, you have to remind us of hope again, and again and again," he said.
"To those of you who choose the path of peace, the United States will support you every step of the way. We will always be the wind at your back."
He added: "This little island that inspires the biggest of things, this little island, its best days are ahead. When peace was achieved here, it gave the entire world hope."
Obama received a rapturous reception from the students and drew laughter as he asked: "What's the craic?".
Fifteen years after the signing of the Good Friday peace agreement which cleared the way for the power-sharing executive in Belfast, the president praised the work of Northern Ireland's political leaders. But he said "ultimately peace is not just about politics, it's about attitudes."
He said: "It's about a sense of empathy, it's about breaking down the divisions we create for ouselves in our own minds that dont exist in any objective reality."
Obama's speech in Belfast's Waterfront Hall came as world leaders gathered for a two-day summit that was supposed to focus on economic issues, including a planned EU/US free trade deal and measures to crack down on tax havens.
However the meetings are likely to be dominated by talks on how to resolve to bloody conflict in Syria. Last week the United States said it intended to start arming the anti-Assad rebel forces, a move strongly opposed by Russia.
David Cameron insisted that no decision has yet been made on whether Britain should send arms, and repeated his assurance that he would "never stand in the way" of the House of Commons voting on any such move.