The Louisiana shootings were unfortunately only the latest in a series of lethal encounters in the United States between law enforcement officers and domestic extremists. Earlier this year, six police officers were shot, one fatally, in Ogden, Utah, after police entered a residence to execute a search warrant. Information from the search warrant affidavit strongly suggests that the suspect, David Stewart, was an anti-government extremist. In 2010, two people associated with the sovereign citizen movement killed two East Memphis police officers and wounded two other officers in a pair of shootouts.
All in all, at least 28 officers have been killed since 2001 in encounters with extremists from one movement or another. The killings have ranged from incidents in which police officers were deliberately targeted by extremists to situations in which police officers happened to encounter extremists engaging in ideological or non-ideological criminal activity.
Overwhelmingly, the perpetrators or suspects in these lethal incidents have been right-wing extremists, adherents of one or another of the primary white supremacist movements or anti-government extremist movements active in the United States today. This is part of a long-term trend since the 1980s, in which right-wing extremists gradually replaced left-wing extremists as the main source of extremist-related officer killings in the United States. Though the figures here are solely for fatalities, anecdotal evidence suggests that the same trends hold for non-lethal extremist-related attacks on police officers as well.
The resurgence of right-wing extremism in the United States since 2009 has undoubtedly contributed to the level of violence: between 2009 and 2012, eight of nine extremist-related officer deaths have been linked to right-wing extremists.
Among right-wing extremists, anti-government extremists have been the most lethal in recent years, perpetrating or suspected of having perpetrated half of the extremist-related officer deaths this century. However, white supremacists have slain nearly as many officers in the same time period and, in a practical sense, represent virtually the same level of threat to officer safety.