President Joe Biden expressed support for the Northern Ireland peace agreement in the face of Brexit-related tensions on Wednesday when he met Ireland’s prime minister Micheal Martin for virtual Saint Patrick’s Day celebrations.

The future of the Good Friday Agreement in Northern Ireland following Britain’s chaotic exit from the European Union was one of the more serious topics in the bilateral session.

It’s “strongly critical to maintain” the accord, Biden told Martin over video link.

But Biden, who is only the second Roman Catholic president in US history and proud of his Irish ancestry, also placed plenty of focus on Saint Patrick’s Day.

Biden began by attending early Mass at a church in his hometown of Wilmington, Delaware before making the trip back to Washington for his long-distance get-together.

Fountains at the White House were colored green and the famous building itself will be lit up in Ireland’s national color after dark.

As in every year since 1952, the meeting included a presentation of shamrocks — small sprigs of clover that symbolize Ireland. An engraved bowl containing the gift was on prominent display in the Oval Office.

“We are determined to fully celebrate the holiday,” a senior Biden administration official told reporters.

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Biden, wearing shamrock in his suit jacket’s handkerchief pocket, had instructed staff to arrange things “as close to the way” they would be if the meeting with Martin was being held in person, the official said.

Biden told Martin he wanted to “celebrate the deep, deep affection Americans have, particularly Irish Americans, for Ireland.”

“It feels strange to have to celebrate apart,” Martin said, expressing hope that by next year they’d be back to visiting each other.

Biden and the Irish leader were touching base on the coordination of efforts to get the global economy back on track through mass coronavirus vaccinations and a “sustainable” recovery, the US administration official said.

The Irish prime minister also heard Biden’s support for the Good Friday Agreement, which largely ended decades of violent unrest in the British province of Northern Ireland.

Biden wanted to express “strong support for this agreement and our commitment to advancing that hard-won peace,” the official said.

There is concern in Washington that a post-Brexit row between London and the EU over customs controls on the border between Northern Ireland and the Republic of Ireland is threatening the complex political balance underpinning the deal.

Martin thanked Biden for “unwavering support for the Good Friday Agreement” and said “I want to move forward with a positive relationship with the United Kingdom.”