A plastun or plastoon (Ukrainian, Russian: пластун) was a Cossack foot scouting and sentry military unit.
The tradition of foot scouts, vanguard troops, and ambushes, together with the term plastuny, belong to the early Cossack history of the Zaporizhian Sich and mentioned, e.g., by Vladimir Dahl in his Explanatory Dictionary of the Live Great Russian language.
Despite this, regular plastun units were not popular, since they did not fit the traditional notion of Cossack pride.
[2] The term was revived in the Soviet Army during the Great Patriotic War and used in the names of several Cossack battalions and regiments.
The only plastun Cossack division of that time was the 9th Krasnodar Plastun Division, which fought in Northern Caucasus, Poland, and Czechoslovakia, and was one of the elite Soviet military units.