BELFAST—In mid-February, Detective Chief Inspector John Caldwell finished coaching his son’s soccer team and was putting soccer balls into the trunk of his car in Omagh, Northern Ireland, when two masked gunmen shot him multiple times in front of his son. British authorities suspect that pro-Irish republicans targeted Mr. Caldwell, who remains hospitalized. On Tuesday, U.S. President Biden will travel to the British province to celebrate the deal’s anniversary along with U.K. Prime Minister Rishi Sunak and Irish Taoiseach Leo Varadkar . Mr. Biden, whose ancestors were Irish, will hail the deal that brought an uneasy peace between a mostly Protestant community that sees itself as British and wants to remain part of the U.K., and a mostly Catholic community that endured decades of discrimination and which views itself as Irish and aspires to see a united Ireland. Within hours of Mr. Caldwell’s shooting, the leaders of the province’s five main political parties—which include pro-British unionist parties and pro-Irish nationalist ones—condemned the attack.

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