In the developing world where armed struggle is viable and, often, actually taking place, yes. In the USA, an “anarchist army” would merely be a bunch of dumbasses who ended up shooting themselves or getting taken down by the feds after falling into some kind of entrapment scheme. At some point in the future, yes, we may need something akin to an American Hezbollah. But only when the horse is firmly in front of the cart. The examples of “armed insurgent” groups we have in the US today are textbook illustrations of how NOT to do it.
Derrick Broze breaks down some history around the Revolutionary Insurrectionary Army of Ukraine, or the Black Army. Derrick asks if it time to organize Anarchist armies.