THE THREAT FROM WITHIN: The mass shooting at a Walmart in El Paso, Texas, has renewed the debate over how to combat terrorism from white extremists.

• Author: Tavernise, Sabrina
• Position: Cover story

In August, a gunman opened fire in a Walmart in El Paso, Texas, killing 22 people. Like many other mass shootings in recent years around the country--from Charleston, South Carolina, to Pittsburgh, Pennsylvania, to Roseburg, Oregon--this one was committed by a shooter with ties to white extremism.

Homegrown terrorism, including by white supremacists, is now as big a threat as terrorism from abroad, law enforcement officials say. But the shooting in El Paso--the largest domestic terrorist attack against Hispanics in modern history--has made it glaringly clear how poorly prepared the country is to fight it.

The U.S. has spent nearly 20 years intensely focused on the battle against Islamic extremists. The terrorist attacks of September 11, 2001, rerouted the machinery of government to fight against threats of violence from the Middle East, Pakistan, and Afghanistan. But those types of attacks have waned in recent years, replaced by violence from white supremacists--an increasingly internet-driven phenomenon of lone wolves, not organized groups, that experts say will prove immensely difficult to combat.

After the shooting in El Paso and another one just hours later in Dayton, Ohio, President Trump pledged to give federal law enforcement authorities "whatever they need" to combat domestic terrorism. But officials say that preventing attacks from white supremacists and white nationalists would require adopting the same type of broad and aggressive approach used to battle international extremism.

"We need to catch them and incarcerate them before they act on their plans," says Rod Rosenstein, the former deputy attorney general. "And we can accomplish that by monitoring terrorist propaganda and communications."

But combating domestic terrorism presents unique challenges that touch many aspects of American life--politics, civil liberties, and business--and involve complicated new questions around the issue of technology.

Fighting Homegrown Terrorism

Federal officials have broad powers to disrupt foreign terrorist plots. They can take preventive action, for example, by wiretapping or using an undercover online persona to talk to people anonymously in chat rooms to search for Islamic militants (also called jihadis).

But domestically, federal officials have far fewer options. A federal statute defines domestic terrorism but carries no penalties. The First Amendment, which protects freedom of speech, makes stopping terrorist acts committed by Americans before they happen more challenging. No government agency is responsible for designating domestic terrorism organizations. And individuals who are considered domestic terrorists are charged under laws governing hate crimes, guns, and conspiracy, not terrorism.

"It's a big blank spot," says Mary McCord, a former top national security prosecutor.

The issue is urgent.

Right-wing extremists killed more people in 2018 than in any year since 1995. And the attack in El Paso and an April shooting in a synagogue...