The thing that most disturbs me about the current administration and all of these ideology-driven mass shootings is that it all comes down to white supremacist ideology. Full stop.
It's not "white domestic terrorism." It's "white supremacist domestic terrorism." These are groups with public membership lists, facebook groups, web presence, etc. We know who these fuckers are and they have incited terrorism that has resulted in the deaths of thousands of people in the United States over the past three or so decades.
This encompasses a wide array of groups:
1) white supremacy-lite (as one can get from Fox News these days and dog whistles from the Trump administration that a few steadfast true believers and trolls still tacitly and overtly support on here)
2) pseudo-mainstream institutionalized white supremacist, misogynist/men's rights, and ethnonationalist organizations that exist under the banner of "free speech" (e.g., "The Alt-Right" that many on here defended through Charlottesville)
3) fringe neo-fascist white supremacist organizations (primarily radical neo-nazi and nativist groups that will never flirt with the mainstream and whose signals I'm not going to boost by naming them).
These are the actors that are enabling, even encouraging this shit.
If any of those characterizations offend you, then you might want to take a closer look at your politics.