They had announced this during the summer. They are reportedly creating five new high-power artillery brigades, one per military district. The 17th High-Power Artillery Brigade had already been created and assigned to the 3rd Corps. It’s unclear to which military district the 3rd Corps belongs - it was said it was part of the 20th Army of the Western MD (which already had such a brigade), Russian sources now state that since August 2023 “parts” of the Corps are part of the Southern MD.

Such a brigade should have two battalions (divisions, in Soviet/Russian jargon) of 203mm howitzers and as many battalions of 240mm mortars, as well as a battalion of 300mm MLRS Smerch.

In any case, “the Northern Military District zone” is a (very diffuse) mistranslation from Russian to English. They actually mean in the “area of the special military operation”. Btw, the Northern Fleet is reportedly going to cease existing as a separate district and its ground formations will join the new Leningrad MD.

When these two sites write about the new Russian formations they are usually reliable though. Aside from the pro-SMO garbage you can obviously find on their feed.

It looks like that post you linked to was deleted, and anyway I think we are mature enough to know how to distinguish new informations (such as the one we’re talking about) of which pro-government Russian medias may have first-hand notice from propaganda and misinformation.