The Enemy Within

On Aug. 3, a lone gunman opened fire at a Walmart in El Paso, Texas, 
killing 22 and injuring 26. The alleged attacker claimed he was seeking to
kill "as many Mexicans as possible." It was the latest in a rising tide of
right-wing violence in the U.S. and abroad. Here, FBI agents arrive at the
Walmart in El Paso the day after the attack to begin their investigation.

Over the last two decades, terrorism has been widely viewed as an international phenomenon largely driven by...