Can Lone-Wolf Attacks Be Prevented?

Stopping lone wolf attacks is exceptionally difficult. When an individual travels abroad to fight in Syria or is in contact with ISIS handlers, U.S. intelligence can pick up on the communication and interaction. And by going abroad to fight for a jihadist group, an individual is committing a crime and can be arrested. Lone wolves, by definition, lack such links. The San Bernardino attackers were not on law enforcement's radar screen before striking. And given permissive U.S. gun laws, even someone like Mateen who allegedly abused his spouse and was repeatedly investigated by the FBI, could legally purchase an automatic weapon because he had not yet openly supported a terrorist group. The FBI is already aggressive against potential terrorists to the point that civil liberties groups criticize it for entrapment and otherwise using stings too aggressively.