Battalion tactical group
A battalion tactical group (Russian: Батальонная тактическая группа, batal'onnaya takticheskaya gruppa), abbreviated as BTG, is a combined-arms manoeuvre unit deployed by the Russian Army that is kept at a high level of readiness. A BTG typically comprises a battalion (typically mechanised infantry) of two to four companies reinforced with air-defence, artillery, engineering, and logistical support units, formed from a garrisoned army brigade. A tank company and rocket artillery typically reinforce such groupings. BTGs formed the mainstay of Russia's military intervention in Ukraine from 2013 to 2015, particularly in the war in Donbas.
In August 2021, Russia's defence minister said the country had about 170 BTGs. Each BTG has approximately 600–800 officers and soldiers, of whom roughly 200 are infantrymen, equipped with vehicles typically including roughly 10 tanks and 40 infantry fighting vehicles.: pp. 11–13
A common misconception is that BTGs are a fixed formation, they have a flexible composition and are similar to German WW2 Kampfgruppe with units added to perform a required role and its the core of the Russian Army. Possible usage of rumoured company sized assault detachments does not really change much as these would become BTGs if the role needed it but does allow more manuever elements.