Biden travels to Ireland and UK to celebrate 25 years of peace -- and his family ties

President Joe Biden is heading across the pond for a long-awaited trip to Ireland, his ancestral homeland, that will feature a heavy emphasis on family in addition to diplomacy.

Biden's visit will be his first to Ireland as president and mark only the second time an Irish-Catholic president has made a visit from the U.S. It also comes nearly 60 years after the first Irish-Catholic president, John F. Kennedy, became the first sitting commander in chief to visit Ireland.

The president left Washington on Tuesday for Belfast, Northern Ireland -- the first stop of his four-day, two-country trip -- alongside his son Hunter Biden and his sister Valerie Biden.

There, Biden will mark the 25th anniversary of the Good Friday Agreement that brought an end to 30 years of sectarian violence on the island known as "the Troubles."

Biden said as he departed Tuesday his top priority for the trip is to "make sure the Irish accords and the Winter agreement stay in place. Keep the peace. That's the main thing."

"President Biden cares deeply about Northern Ireland and has a long history of supporting peace and prosperity. As a U.S. senator, Joe Biden was an advocate for how the United States can play a constructive role supporting peace," White House spokesperson John Kirby said Monday, previewing the trip.

Biden's visit to Northern Ireland will also focus on "the readiness of the United States to support Northern Ireland's vast economic potential to the benefit of all communities," according to the White House.

The economic focus of Biden's visit is particularly notable as Ireland, a member of the European Union, and Northern Ireland, part of the U.K., are still dealing with the fallout from Brexit, when the U.K. left the EU.

Earlier this year, a trade deal called the Windsor Framework was struck to prevent a strict land border from being reinstated on the island and to address some of the outstanding trade concerns remaining from Brexit.

A so-called "hard border" between Ireland and Northern Ireland, some feared, could undermine the 1998 peace agreement and see tensions reignited between mostly Protestant "unionists" and mostly Catholic "nationalists" in Northern Ireland.

Biden previously praised the Windsor deal as "an essential step to ensuring that the hard-earned peace and progress of the Belfast/Good Friday Agreement is preserved and strengthened."

After lowering the terrorism threat level to "substantial" last year, Northern Ireland has recently raised it back to "severe," meaning an attack is highly likely, based off an MI5 intelligence assessment. But Kirby on Monday downplayed any concerns about security when asked about Biden's travel.

"We don't ever talk about security requirements of protecting the president, but the president is more than comfortable making this trip and he's very excited to do it," Kirby said.

Following his time in the U.K., Biden will head to the Republic of Ireland later this week, where he will meet with President Michael D. Higgins and Taoiseach Leo Varadkar as well as address a joint session of the Irish legislature.

"Today, one in 10 Americans claim Irish ancestry and Irish Americans are proudly represented in every facet of American life. Ireland's a key economic partner of the United States, and the United States and Ireland are working closely together to make the global economy more fair," Kirby said in his preview of the trip.

He also singled out Ireland's contributions to Ukraine amid Russia's invasion.

"The Irish government has been strong supporters of Ukraine, providing vital non-lethal assistance including medical supplies, body armor and support for Ukraine's electric grid, as well as their agriculture," he said.

"They have supported EU sanctions on Russia and the people of Ireland have generously welcomed nearly 80,000 Ukrainians, offering refuge to those who were forced to flee their homes in search of safety," he said.

But perhaps the bigger focus of Biden's trip will be tracing his connections back to Ireland, mainly through two families on his mother's side: the Finnegans and Blewitts.

Biden is expected to meet with relatives and visit "places of significance to the Finnegans of County Louth and the Blewitts of County Mayo," according to a White House official.

In County Louth on Wednesday afternoon, Biden will visit Carlingford Castle; on Friday in County Mayo, he will visit Our Lady of Knock and the North Mayo Heritage and Genealogical Center's family history research unit. (He returns to Washington on Saturday.)

He is also expected to deliver remarks near St. Murdoch's Cathedral in County Mayo that "celebrate the deep, historic ties that link our countries and people," White House press secretary Karine Jean-Pierre said in a statement announcing the trip.

That cathedral has deep ties to Biden's family -- some relatives were baptized there, and his great-great-great grandfather Edward Blewitt sold 27,000 bricks to the cathedral that were used in its construction, which ultimately helped fund the family's voyage to America.

Even the most casual observers of the president have likely heard him boast of his Irish heritage. In nearly all his remarks, he will often quote members of his Irish family or some of his favorite Irish poems and literature, like Seamus Heaney's "The Cure at Troy."

"My colleagues up in the United States Senate used to kid me because I was always quoting Irish poets on the floor. They thought I did it because I was Irish. That's not the reason. I did it because they're the best poets in the world," Biden has joked.

In the past he has spoken about his Irish roots as "part of [his] soul" and "how [he] was raised."

The focus of his political pitch of "dignity" for all Americans is also based on his heritage.

"[I]t gets back to a word that's probably overused in my house -- as my grandfather would say, 'Maybe it's the Irish of it.' The word 'dignity.' The simple dignity," Biden said in May of his policies focused on trying to improve the middle class.

During his time in Ireland, Biden will "discuss how a fierce pride in being Irish and a value system that says everyone is entitled to be treated with dignity and respect have been passed down to each generation," the White House official said of the trip.

"He will also discuss how the Irish-American story -- of enduring difficult times but marching forward towards a better tomorrow -- speaks to our shared past, present and future," the official added.