Earlier quoted context omitted.
What we're seeing is a "stochastic insurgency" where loosely affiliated groups and individuals conceive, plan and execute infrastructure attacks and targeted assassinations. Relatively little operational coordination; but lots of online showing support and post-crime support. I hope all congressional representatives and local government officials are reviewing their safety plans.
You can conclude all of that from one attack? Where are the other infrastructure attacks? Or targeted assassinations?
Both stopped by intelligence services, but that doesn't stop them being data points for people being extremists.
Not saying there is a guarantee this was people with the same objectives, but it seems like a plausible theory. I wouldn't make strong assertions as though it was fact, but I also wouldn't act like there hasn't been a trend recently.