The Washington Post’s Jonathan Capehart writes: 

The Department of Homeland Security warned that “lone wolves . . . embracing violent right-wing extremist ideology are the most dangerous domestic terrorism threat in the United States.” It went on to say that “white supremacist lone wolves pose the most significant domestic terrorist threat because of their low profile and autonomy — separate from any formalized group — which hampers warning efforts.” And it noted that military expertise and knowledge made lone wolves especially dangerous.