Every victim of terrorism is innocent, and every one is to be mourned. But the bombing in Manchester, England, on Monday night that killed teenage or even younger fans of the pop star Ariana Grande, many accompanied by their parents and some clutching the pink balloons Ms. Grande had sent sweetly raining down at the end of her concert, is particularly wrenching.

By Tuesday, 22 people had died, and 59 others had been hospitalized, some with life-threatening injuries. The dead included 8-year-old Saffie Rose Roussos, who had come with her mother and older sister, and 18-year-old Georgina Bethany Callander, who had posted an image of her brand new driver’s license on Instagram.

The Islamic State said one of its “soldiers” had carried out the bombing, which took the life of the man British police officials believe was behind it, Salman Abedi, a 22-year-old whose parents emigrated from Libya. It is still unclear whether Mr. Abedi acted alone or as part of a network. No one yet knows what motivated him to commit such a horrific deed. It is also unclear whether the Islamic State’s claim is legitimate. Only further investigation can answer these questions.

Meanwhile, as hard as it is amid the shock and the mourning, it is important to recognize this attack for what it is: an attempt to shake Britain — and, by extension, the rest of Europe and the West — to its core, and to provoke a thirst for vengeance and a desire for absolute safety so intense, it will sweep away the most cherished democratic values and the inclusiveness of diverse societies.