Joe Biden has said he will use his visit to the island of Ireland to “keep the peace”, as he left the US for his four-day trip.
The US president invoked the importance of the Good Friday Agreement and the recently negotiated Windsor Framework as he prepared to set off for Northern Ireland.
Biden will arrive later on Tuesday as he begins a visit marking the 25th anniversary of the Good Friday Agreement.
Biden will also travel to the Republic of Ireland, where he will carry out a number of engagements during his four-day stay, including visiting Co Louth and Co Mayo – from where his ancestors hail.
His son Hunter Biden and sister Valerie Biden Owen are believed to be accompanying him for the trip.
Biden, speaking to reporters before his departure, said that his top priority was to “make sure the Irish accords and the Windsor Agreement stay in place, keep the peace”.
“That’s the main thing,” he said.
Prime Minister Rishi Sunak will meet Biden when Air Force One touches down in Northern Ireland on Tuesday evening.
The two leaders will also hold a meeting on Wednesday before Biden gives an address at Ulster University’s new £350m Belfast campus.
Sunak will not attend Biden’s keynote speech, with Downing Street on Tuesday denying that the engagement between the pair would be “low-key”.
The visit coincides with the anniversary of the Good Friday Agreement, which largely brought an end to the Troubles, in Northern Ireland in 1998.
However, the Stormont powersharing Assembly, which was established in the peace deal, is not currently operating due to a protest over post-Brexit trading arrangements by the DUP, the largest unionist party in Northern Ireland.
It is expected that Biden will hold a meeting with Northern Ireland’s main political parties before the Ulster University talk.
A major security operation will be in place for Biden’s visit, with more than 300 officers from the rest of the UK being drafted into Northern Ireland.
The PSNI has also warned of significant traffic disruption in Belfast during the presidential visit, with a number of roads in the city centre already closed.
After he leaves the city on Wednesday, Biden will cross the border to attend engagements in Co Louth.
The president has traced his ancestral roots to the area and he will tour Carlingford Castle in the county before spending the night in Dublin.
He is then expected to visit Irish President Michael D Higgins on Thursday.
It has been announced that Dublin’s Phoenix Park will be closed for 24 hours from 5pm on Wednesday to facilitate the visit.
Higgins’ official residence is within the park’s grounds.
The White House said Biden will take part in a tree-planting ceremony and ringing of the Peace Bell at the president’s official residence, Aras an Uachtarain.
Following that ceremony, he will meet again with Taoiseach Leo Varadkar, whom Biden recently hosted for St Patrick’s Day.
Biden will address the Irish parliament and attend a banquet dinner at Dublin Castle on Thursday evening.
The president’s trip will conclude with a visit to Co Mayo, where he has also connected with distant cousins, on Friday.
He will tour the Sanctuary of Our Lady of Knock and visit the North Mayo Heritage and Genealogical Centre’s family history research unit.
He will then make a public speech at St Muredach’s Cathedral in Ballina.