Michael Kugelman is deputy director and senior associate for South Asia with the Woodrow Wilson International Center for Scholars in Washington, DC. You can follow him on Twitter @michaelkugelman. The views expressed are his own.

(CNN) More than 48 hours after the Easter Sunday massacre in Sri Lanka, a devastatingly well-coordinated assault that targeted churches and hotels around the country, the shock still lingers.

It was by far the deadliest attack to strike Sri Lanka since the dark days of its brutal 26-year civil war, which ended in 2009. And it shattered the relative stability that had prevailed in the country in the subsequent decade.

Information provided by Sri Lankan officials has linked a small and little-known extremist outfit named National Tawheed Jamath (NTJ) to the attack. Indeed, NTJ is no jihadist juggernaut; it's an entity mostly known for defacing Buddhist statues

It's downright terrifying that such a modest and under-the-radar organization previously known for little more than vandalism could pull off such a sophisticated and catastrophic attack.

In recent years, similarly complex and well-choreographed mass-casualty assaults across the globe have been carried out by the household names of the terrorism world -- al-Qaeda, ISIS, Lashkar-e-Taiba, al-Shabab, Boko Haram, the Taliban, and so on.

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