Violence first broke out last week amid rising tensions relating to Brexit and anger over a decision by police not to prosecute leaders of the Irish nationalist party Sinn Fein for allegedly breaking coronavirus restrictions during the funeral of a former leading IRA figure.

State Department spokesman Ned Price told a briefing that Washington was deeply concerned by the violence and called for calm.

“As the United Kingdom and the EU implement Brexit related provisions, this administration encourages them to prioritise political and economical stability in Northern Ireland,” he said.

“President Biden has been unequivocal in his support for the Belfast and Good Friday agreement, which was a historic achievement. We believe that we must protect it, and we believe that we must ensure it doesn’t become a casualty of Brexit.”

The 1998 accord largely brought an end to three decades of conflict between pro-Irish, mainly Catholic nationalists and pro-British, mainly Protestant unionists in which about 3,600 people were killed. The talks were chaired by U.S. special envoy George Mitchell. “We remain … steadfast supporters of a secure and prosperous Northern Ireland, in which all communities have a voice and all communities enjoy the gains of a hard-won peace,” Price said. (Reporting by Simon Lewis and Daphne Psaledakis; Writing by Humeyra Pamuk and Angus MacSwan; Editing by Daniel Wallis)