Sissi is a Finnish term for a soldier who conducts guerrilla warfare operations behind and within enemy lines. The word is derived from Russian word “Shish” meaning forest bandit.
Present-day Finnish Army Sissi units are trained to gather intelligence (LRRP), conduct raids, stop border infiltrators, and prevent enemy efforts to sabotage mobilization. During war the unknown number of guerrilla trained soldiers from Sissi battalions deploy and operate as small groups as well as companies when raiding important enemy positions.
Using the term guerrilla with Finnish Sissi troops is somewhat misleading, since Sissi forces are a part of the normal army reserve simply trained for operations behind enemy lines. Sissi forces use guerrilla tactics, but could also be called commando or military scout.
In Finland Sissi is used as an umbrella term for all unconventional military applications. E.g. MRE is called Sissi food.
Sissi troops are trained in several brigades under the Finnish Defence Forces. Finnish Border Guard, which is under the Ministry of the Interior, also trains Sissi-troops in Frontier Guard Companies.
Conscript training in these units is 6 to 12 months long. Leaders of guerrilla warfare platoons and squads serve 12 months whereas crew members serve 6 months. Also the medical personnel (as also in scout units) serve 12 months, reaching the level of an NCO.
The training is harder than in other infantry companies, including survival training in the forest during every season of the year. Sissi NCO/Officer training includes signals, demolitions, extended small arms training as well as escape & evasion techniques and ambush tactics.
Trainees can specialize further into Reconnaissance, Sniping, Dog handling etc. Since forest is the element for sissi troops, men and woman with hobbies like hunting, fishing, hiking and Scouts are selected to sissi training.
In addition to specially trained sissi troops, everyone in Finnish army receives basic training in survival and sissi tactics. All troops and soldiers in Finnish army are capable of moving from normal warfare to sissi tactics if they are, for example, encircled or their main forces or command structure is destroyed.
Note that the Sissi battalions as a whole are non-airborne, the only paratrained troops of Finland are Utti Jaeger Regiment’s parajaegers and specialjaegers. These Ranger/Guerrilla Warfare Companies (concerning this article) are units that do not attend any courses in Utti, but do conduct guerrilla/recon missions during war time.