Authorities in Northern Ireland uncovered what could be evidence of a dissident plan for violence ahead of a visit by President Joe Biden, according to local reports.

Leaders, including Biden, are expected to gather in Northern Ireland this week to celebrate the 25th anniversary of the Good Friday Agreement, an accord which effectively put an end to a 30-year period of near-constant sectarian violence known as “the Troubles.”

But a dissident group, known as the New IRA, is reportedly suspected of putting together a terror plot to disrupt those plans.