Adam Serwer: Trump’s caravan hysteria led to this.

The landscape behind these attacks is complex, though. They emerge from a collection of far-right factions held in equipoise between cooperation and competition by their shared support for Trump. Understanding these factions can help shed light on what is happening, and what lies ahead for a fractured American body politic.

I recently analyzed about 30,000 Twitter accounts that self-identified as alt-right or followed someone who did, for VOX-Pol, the European academic network studying extremism on social media. The results were illuminating.

The alt-right is often described as a movement or an ideology. It is better understood as a political bloc that seeks to unify the activities of several different extremist movements or ideologies. While it is international in reach, its center of gravity is in the United States. Because the alt-right is a bloc, it has to be understood by mapping its components and analyzing how they overlap and how they differ. (Not everyone who associates with the bloc online self-identifies as alt-right.)

The alt-right is overwhelmingly white nationalist. The most influential account included in the data set of alt-right Twitter followers was that of Richard Spencer, the avowed white nationalist who coined the term alt-right. Six of the top 20 most influential accounts were owned by white nationalists on Twitter using their real names. (The VOX-Pol policy on social-media research discourages the publication of account handles.) Seven more were pseudonymous accounts tweeting primarily about white nationalism. The 12th-most-used hashtag (out of almost 220,000) was #whitegenocide.

But below the top 0.5 percent of users and themes, other metrics pointed to dissonance. A number of different types of nationalist and white-nationalist movements were represented in the network. While all white nationalists identify with white, not all identified with the same nation, which is one reason to prefer the term white nationalist to white supremacist in many cases. Many Dutch, Swedish, and Australian accounts were found in the network, as well as many accounts self-identified as white South Africans. These regional movements can have vastly different priorities and hot-button issues while still sharing core racist ideological elements.

Peter Beinart: Trump shut programs to counter violent extremists.

Even within American circles, there were wide variations. Some movements were neo-Nazi or Nazi-nostalgic. Others were associated with the Ku Klux Klan. Many chose to try to camouflage their racism as “race realism,” while others were not concerned with subtlety. While these groups share white supremacy as a core belief, they call for very different tactical approaches and strategic outcomes (ranging from institutionalizing racial preferences to genocide). These differences have historically made it difficult for American white nationalists to cooperate with one another, something the alt-right umbrella tries to remedy, with mixed results.