Northern Irish leaders struggle to quell worst violence in years

Northern Ireland's power-sharing government put aside factional differences on Thursday to call for calm after frustration among pro-British unionists over post-Brexit trade barriers helped trigger some of the worst violence in the region in years.

Despite the appeals, clashes spread further into Irish nationalist areas on Thursday night where police responded to petrol bomb and stone attacks with water cannon. The White House joined the British and Irish governments in urging calm.

Hundreds of youths in the British province's capital Belfast set a hijacked bus on fire and attacked police with stones on Wednesday in scenes reviving memories of decades of sectarian and political strife that claimed some 3,600 lives prior to a 1998 peace deal.