For at least a year now, Sunni extremist gunmen have been methodically attacking members of the Hazara community, a Persian-speaking Shiite minority that emigrated here from Afghanistan more than a century ago. The killers strike with chilling abandon, apparently fearless of the law: shop owners are gunned down at their counters, students as they play cricket, pilgrims dragged from buses and executed on the roadside. …

The bloodshed is part of a wider surge in sectarian violence across Pakistan in which at least 375 Shiites have died this year — the worst toll since the 1990s, human rights workers say. But as their graveyard fills, Hazaras say the mystery lies not in the identity of their attackers, who are well known, but in a simpler question: why the Pakistani state cannot — or will not — protect them. …

The government, already battling Taliban insurgents, insists it is taking the threat seriously. During the recent Mourning of Muhurram, when Shiites parade through the streets over 10 days, the Interior Ministry imposed stringent security measures such as blocking cellphone signals for up to 12 hours — to try to prevent remote bomb detonations — and banning doubled-up motorcycle riding. Even so, Sunni bombers struck at least five times, killing at least 50 Shiites and wounding several hundred. The Pakistani Taliban claimed responsibility for the biggest attacks, highlighting an emerging link between that group and traditional sectarian militants that has worried many.