Russia's army in the field. It is a warfare doctrine developed since Cambrai that relies on the synchronized use of multiple weapon systems to attack enemy positions. A video showing the doctrine in operation against an entrenched defense line of mines, armor and mechanized infantry is worth a thousand words. Note especially the use of close air support to eliminate deep, high-value targets, such as artillery batteries and ammo dumps, supporting the enemy's defensive line, similar to what Ukrainian forces may encounter if they attempt to sever the land bridge to the Crimean peninsula. It is only sixty miles from Donetsk to Mariupol, but that sixty miles is filled with Russian military assets. When Ukrainian forces stopped an armored assault at Vuhledar, they defeated another ill-planned, poorly executed maneuver by Russian forces. Video shows BMPs driving over RAAM (Remote Anti-Armor Mines) sown via 155mm artillery shells. Combined arms doctrine aims to prevent such failures.
Warning: A lot of military jargon is used in this video, but the depiction of various assets used in the phased, synchronized brigade assault gives the viewer an idea of the scope of this complex maneuver. The Ukrainians are smart and resourceful fighters, but you cannot learn the details of this mechanized war dance overnight.