Don't tell anyone, but all Infantry is 'disposable'
However, one fairly broadly implemented organizational change observed by RUSI is that the Russian Army is informally
categorizing Russian infantry into four types of units by role: specialized, assault, line, and disposable.
Firstly, RUSI cautions that characterizing Russian offensive assault tactics as “human wave” tactics is simplistic and misleading. Russia is not generally running large groups of infantry straight at Ukrainian positions.
Instead, Russian tactics revolve first around the deployment of “disposable infantry.” These soldiers are LPR/DPR militia, barely trained Russian mobilized or conscripted infantry, or Wagner convict units. These soldiers are not sent forwards in large groups, but generally in teams of 3 soldiers. Carrying ammunition and some supplies, they rush forwards through enemy fire and try to establish dug-in positions progressively closer to the main Ukrainian defensive position.
These attacks by disposable infantry are supported by “Specialized” troops—snipers, grenade launchers, rocket-propelled grenade teams, heavy machine guns, and other specialized weapons that require a higher degree of skill.
The Specialized infantry keeps their distance to preserve their safety due to their high value but aims to inflict losses while Ukrainian defenders are focused on the approaching disposable infantry units.
If the Disposable infantry is eliminated, artillery barrages are directed at identified Ukrainian strong points, and the attack starts over.
By repeating this cycle over and over, gradually the Russian commander will obtain a detailed understanding of the strengths and weaknesses of the Ukrainian position. Furthermore, the waves of disposable infantry will gradually develop a series of protected dug-in positions with stocks of grenades, small arms ammunition, and water that are closer and closer to the Ukrainian line of defense.
Once the Russian commander identifies a weak point, he can call on his assault infantry and, if available, armored units to launch an attack. Assault Infantry are well-trained Russian infantry units, usually formed from veterans before the start of the war. Armed with the best equipment, better training, and with a tank and/or IFVs in support, assault infantry will aim to penetrate the Ukrainian defense and overrun the enemy position with as few casualties as possible, forcing a Ukrainian retreat.
Wagner units have such distinctions, where a small group of elite ex-VDV or Spetsnaz troops form elite assault units, while the majority of Wagner soldiers are composed of convict disposable infantry. In Bakhmut, Wagner accelerated its offensive operations in late December 2022 by attaching units of VDV infantry to its convict battalions, to increase the number of available assault infantry.
If the Russians had a few platoons or tanks and mechanized infantry in reserve, at this dangerous moment, the Russians could exploit this tactical breakthrough by pursuing the retreating Ukrainians to attempt to overrun the position and achieve an operational breakthrough.
What is very clear is that the Russian army no longer has this ability.
So instead, the Russian line moves forwards (perhaps as little as a few hundred meters), and the process starts all over again against the next line of Ukrainian defense.
Line infantry is the last unmentioned infantry type, primarily because it generally does not play much of a role in assaults. They are composed of more experienced conscripts and less trained contract soldiers who generally are organized into mechanized infantry or combined arms units. Unlike Assault infantry, Line infantry have not received training on assault tactics.
Line infantry are frequently deployed together with disposable infantry units, and are given the hard labor of constructing defensive fortifications and manning defensive positions. They differ most greatly from disposable infantry in their greater experience, and in that they are prioritized for preservation when selecting units to make frontal probing assaults.
RUSI observes that no formal designation of these unit types exists, as it would be politically untenable to designate certain units as “disposable,” even in Russia.
Quick Explainer: Russia's Four Types of Infantry--Specialized, Assault, Line, and Disposable