Yugoslav military doctrine assumed an omnidirectional threat, but its strategy and tactics presupposed a heavily armored and mechanized Soviet or Soviet-led Warsaw Pact invasion, entering from the northeast and driving southwest to split the country. Major exercises were held every few years to test the doctrine in action. Special attention went to coordinating combat actions between YPA and TDF units.
Yugoslavia's defense strategies were circumscribed largely by geography and the size and capabilities of its forces (see fig. 15). However, military leaders believed their strategy and tactics to be appropriate and viable, and their manpower and equipment to be sufficient to defend against anticipated threats. Also, the experience of the wartime Partisans proved the feasibility of TDF for national defense.
The events of 1968 changed the previously exclusive emphasis on a regular army, conventional war, and the defense of strategic areas in the north of Yugoslavia. The developed northern part of the country was recognized as virtually indefensible. The major cities, industries, and communications networks situated on the Danubian plain would be easy strategic targets for a potential attacker, as such assets were in the 1968 invasion of Czechoslovakia.
TND doctrine required the YPA to blunt or at least slow an enemy invasion in the north. While conventional forces fought defensive actions along a nationwide front, one to three million citizen-soldiers would mobilize in TDF units. Small TDF units would engage alongside beside regular troops in their local areas, with TDF tactics emphasizing mobility and light antipersonnel and antiarmor weapons. The terrain would become increasingly favorable to the defenders as fighting shifted from the Danubian plain to the less developed mountainous and forested areas of the Adriatic littoral and southern Yugoslavia. On this terrain the tanks, mechanized infantry, and self-propelled artillery of a superior enemy force would be less effective.
When possible, TDF units would coordinate their actions with the YPA. This coordination was practiced in several major nationwide maneuvers in the 1970s and 1980s. The TDF units also were capable of continuing action independently under local commanders. According to doctrine, the TDF would resort ultimately to protracted guerrilla warfare against an invading force to turn the blitzkrieg into a costly and lengthy occupation. Independent TDF units would attack occupying forces in as many places as possible and carry out harassing actions, ambushes, and sabotage behind enemy lines. Yugoslav military authorities believed that, based on current estimates of relative military power and the Partisan experience of World War II, two million enemy troops would be required to subjugate the country. Such a commitment would deter a potential aggressor from invading Yugoslavia while managing other strategic requirements.
Data as of December 1990