Taoiseach Leo Varadkar and British Prime Minister Boris Johnson have both spoken positively after a day of talks at Stormont.
Mr Johnson described it as "a day of real hope" for Northern Ireland and its people, while Mr Varadkar said it was "a really good day for Ireland and the UK" as the Good Friday Agreement was back up and running with power-sharing in place.
They were speaking after a meeting at Stormont, which also included the Northern Ireland First and Deputy Ministers.
During his visit, Mr Johnson hailed the "wonderful" compromise that triggered the return of powersharing.
"Never mind the hand of history on my shoulder... I see the hand of the future beckoning us all forward," he said.
"And I hope that with goodwill and compromise and hard work on all sides it will be a very bright future indeed."
The Taoiseach said it was a "really good day for Ireland and the UK".
"The Good Friday Agreement is visionary and the Good Friday Agreement is working again," he said.
Powersharing here in Northern Ireland, North South co-operation, is going to resume, and we're going to beef up and deepen co-operation between Britain and Ireland in the interests of everyone who lives on these islands.
The parties sealed an accord restoring the devolved institutions following a three-year suspension which has seen public services like health and education suffer.
"I want to say how grateful I am to all the parties, and everybody here in Northern Ireland, for the way they have compromised and the way they have worked together to get Stormont up and running again," Mr Johnson said.
"It's shown a willingness to trust each other and to set aside difference, and I think it's absolutely commendable and wonderful to see."
Stalled legacy mechanisms related to Troubles killings, agreed by the region's parties as part of the 2014 Stormont House Agreement, are finally set to be implemented as part of the deal to restore powersharing.
They include an independent investigation unit to establish if any prosecutorial opportunities remain, and a truth recovery body to help families find out more details about the deaths of their loved ones in cases where prosecutions are unlikely.
Mr Johnson was asked about the prospect of more veterans being prosecuted.
He stood by the Conservatives' general election manifesto pledge to protect armed forces veterans from the 30-year conflict from unfair prosecutions without new evidence.
The Prime Minister said the Stormont parties had done a good job balancing that with giving confidence to victims of violence who are seeking answers.
He said it is vital that public spending is properly monitored to ensure no repeat of the botched and overspending green energy scheme that caused the Stormont collapse three years ago.
He acknowledged there could be checks on goods crossing the Irish Sea that were destined for the Republic of Ireland as a result of Brexit, but insisted a deal with Brussels could mean they are not necessary.