Iraqi security forces repelled an assault by militants Wednesday on the highly sensitive city of Samarra, witnesses said.

Samarra is home to a revered Shiite shrine that was bombed in 2006, sparking a sectarian conflict between Iraq’s Shiite majority and Sunni Arab minority that left tens of thousands dead.

It lies just 110 kilometers (70 miles) north of Baghdad on the main highway from the country’s second city Mosul, which jihadists seized on Tuesday. […]