Since DVE might be a relatively new term for emergency managers, I thought it would be good to give you two resources. The first is this official DHS National Terrorism Advisory System Bulletin from January.
Then today I listened to this podcast: "The Threat Of Domestic Terrorism
I think one of the things she points out at the end of the recording is that there were "unaffiliated" individuals who participated in the Jan. 6 riot at the capitol. The near-term danger is that these people are ripe for recruitment into a more nefarious group — without the recruit understanding the background and full intent of the organization doing the recruitment. She uses the example of militias as one type of group that on the surface may seem totally service and patriotic oriented, while not understanding their being committed to overthrowing the government.
For those who read or no longer read my blog who think I've gone "political" in my thinking, note that Elizabeth Neumann was a Republican appointee at DHS under two Republican administrations, not some Democratic plant within the organization. Personally, I'm drawn to people who serve the nation first over a political party.