ABUJA, Nigeria — Nearly four years into Nigeria’s bloody struggle with Islamists in its impoverished north, a new threat has emerged with deadly implications, this time for Westerners as well as Nigerians: local militants who openly claim to be inspired and trained by Al Qaeda and its affiliate in the region.

Having split off from Boko Haram — the dominant Nigerian extremist group responsible for weekly shootings and bombings — this new group, Ansaru, says it eschews the killing of fellow Nigerians.

“Too reckless,” said a young member of Ansaru. His group evidently prefers a more calculated approach: kidnapping and killing foreigners.

Just days before, his group had methodically killed seven foreign construction workers deep in Nigeria’s semidesert north. The seven had been helping to build a road; their bodies were shown in a grainy video, lying on the ground.