Opinion | After the Terror in Barcelona

There are always many questions after a terrorist attack, some never to be answered. Why a promenade in Barcelona and the seaside town of Cambrils? Why now? Were the terrorists compelled to act hastily after a more insidious plot collapsed when a bomb they were making in a nearby town exploded prematurely on Wednesday?

These are matters police and antiterrorist forces in Spain and elsewhere are sure to explore as they seek to combat the blight of Islamist terrorism. And though the horror of attacks like Thursday’s on the tourist-packed Las Ramblas in Barcelona, where at least 13 people were killed, dominate attention, authorities have made major gains in Europe in identifying and tracking potential terrorists and in preventing attacks.

But the hard truth is that there is no sure defense against young men filled with resentment and fired up with the lethal propaganda of militant Islam, especially as they turn to rudimentary weapons like the vehicles in Barcelona and Cambrils, or before that in Nice; the Christmas market in Berlin; Westminster Bridge in London; or Drottninggatan, a major pedestrian street in Stockholm.

There are questions but there are no longer so many mysteries. We know where extremism breeds, who fans the flames. We know that the terrorists strike in places like Las Ramblas, where people of all ages and nationalities gather simply to enjoy themselves, and that they use the most banal instruments, like the rented van in Barcelona, to spread the greatest fear. At least 80 people from over 30 countries were injured in Barcelona. To honor the lives lost, thousands of people returned to Las Ramblas on Friday and chanted in the Catalan language, “We are not afraid.”

Though the Islamic State claimed responsibility, it does not require a global network or intricate training to drive a van into a crowd. Just blind hatred. So we know there will be more attacks, more shaky images of people fleeing and screaming, more candles burning on bloodstained sidewalks so long as terrorist organizations like the Islamic State or Al Qaeda continue to spread their murderous blend of religious extremism, victimhood, vengeance and violence among disaffected youths.