Yesterday, in the Texan border town of El Paso, a young white supremacist opened fire at a Walmart, killing 20 people and injuring dozens more. His intention, per a manifesto he left on the website 8chan, was to exact revenge against “the Hispanic invasion of Texas,” to forestall what he called “cultural and ethnic replacement,” and to “reclaim my country from destruction.” His actions, he confirmed in the first line, were inspired by “the Christchurch shooter and his manifesto.” The killer was the second gunman to cite Christchurch as an inspiration in the last six months. The perpetrator of the massacre at California’s Poway Synagogue — also a devotee of 8chan — made exactly the same claim in April. In the Internet era, malevolence tends to echo.

During the Cold War, Ian Fleming observed that “once is happenstance, twice is coincidence, the third time it’s enemy action.” So it is here. It would be both too glib and too simplistic to smother the details of these attacks beneath a single word such as “horror” or a catch-all euphemism such as “senseless.” In America, as abroad, we see our fair share of inexplicable violence. But the patterns on display over the last few years have revealed that we are contending here not with another “lone wolf,” but with the fruit of a murderous and resurgent ideology — white supremacy — that deserves to be treated by the authorities in the same manner as has been the threat posed by militant Islam.