Friday’s bomb attack in Oslo that killed at least seven people — and what police say is a related shooting attack at a youth camp on an island outside the Norwegian capital that left an larger number dead — are widely assumed to be the first jihadist terror strike on Western soil since the death of Osama bin Laden. If that suspicion, based on recent events in Norway and its neighborhood, proves to be correct, it might confirm the increasingly diffuse and localized nature of al-Qaeda, and an inclination to use local assets — or even simply to inspire local sympathizers — to strike at less protected targets in the West. In the big-picture arc of the decade since 9/11, it’s a strategy of diminishing returns for the jihadists, but the grim tidings from Oslo on Friday are a reminder that even a scattered jihadist movement whose capabilities are massively degraded will still occasionally get lucky.