Community Defense Requires a Community
More often than not, I see people approach community defense in the opposite order. That is, defense first, then community. There are a lot of reasons why this is a bad idea, and in the end it frequently hurts the community that people are supposedly defending.
Community defense is a complex subject. Every community's threats, needs, and situation are wildly different, and change dramatically over time - sometimes incredibly quickly. Serving the community requires a commitment to the community first, and a willingness to change tactics as the community's needs evolve. Someone who started with "defense" and then later located a "community" will find that their commitment is in the same order. Starting with "I want to defend, who can I find to defend" ultimately means a commitment to a tactic, not the people it's supposed to serve.
Given the wide variety of needs that community defense might serve, this commitment to a particular tactic often means the defenders aren't actually wanted by the community because they don't fit into the community's needs and plans. Unfortunately, this has rarely stopped people from showing up and trying anyway. There are many cases where a community doing its best to survive a bad situation has suddenly had a group of armed "community defense" activists appear and ratchet the situation up a few notches, whether the community asked for it or not. An after-action review of the George Floyd uprisings found that some security teams became their own centers of power, rather than supporting the community and its goals.
Self-appointed security teams also posed challenges, sometimes mixing guns with drugs or alcohol, or taking their own decisions in conversation with outside officials.
The common denominator is that people came to the idea of "defense" first, and then tried to find a community they could do it for (or, more accurately, do it to). Unless it starts with the community and its needs, community defense doesn't live up to its name.
Even if these "backwards" actions are - usually by sheer luck - more or less successful in the short term, getting the order of "community" and "defense" wrong can be deeply harmful in the long term. Community defense generally requires a deep and lasting commitment to the community, a commitment that's hardest to maintain exactly when it's most needed.
Community defense is rarely fun or glamorous, and when the community is most in need, the people who are here for the "defense" are likely to disappear. If the community chose its strategy counting on defenders being present, this can lead to catastrophe.
In the end, community defense can only succeed when the community itself is capable of its own defense. Nobody knows what a community needs and has a commitment to its success like its own members. Defend your community because you care about the community - not about the idea of defending it.