How Swedish Air Force’s underground facilities Inspired the Construction of Bihac (Zeljava) Underground Yugoslav Air Force Base

How Swedish Air Force’s underground facilities Inspired the Construction of Bihac (Zeljava) Underground Yugoslav Air Force Base

By Dario Leone
Jun 13 2024
Sponsored by: Helion & Company
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The Underground Yugoslav Air Force Base

The air force of Tito’s Yugoslavia has had many different peculiarities – from a unique Cold War position of having operated a mix of US, Soviet, and indigenous aircraft and equipment, to the changeable strategies in case of war.

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One such feature was an entire underground air base constructed inside a hill near the town of Bihac, in western Bosnia. ‘The Object’ was the core, the heart, of this air base: it housed four MiG-21 squadrons for nearly 25 years, until the civil war tore Yugoslavia apart.

‘The Object’ was built as the outcome of Yugoslav military efforts to build up its independent defence capabilities, especially the air force which was regarded as the strategic tool in keeping Tito’s Yugoslavia’s independence from both Cold War blocks.

As explained by Bojan Dimitrijevica and Milan Micevski in their book Tito’s Underground Air Base Bihac (Zeljava) Underground Yugoslav Air Force Base 1964-1992, during the mid-1950s, the top brass of the JRV i PVO (colloquially known as the RV i PVO since 1959) concluded that in the event of a major war – whether against NATO or the Soviet Union and its allies of the Warsaw Pact – its fleet of combat aircraft would require adequate shelters. Already gradually developing, this idea attracted evermore attention by 1958, when the JNA created a new set of defence plans for what it termed the ‘whole-scale people’s defence war’ (opštenarodna odbrana). This concept expected that the next war against Yugoslavia was certain to see massive deployment of nuclear weapons of different yields, even on the tactical level, and strongly influenced the training of the JNA and the RV i PVO over the following decade.

Obsessed with nuclear warfare

Indeed, the longer they observed the developments around them during the following years, the more the Yugoslav military strategists became obsessed with nuclear warfare – to a degree where their only, and logical, conclusion was that they had to construct as many underground facilities as possible in order to protect their forces. The result was the decision to construct extensive underground military installations all over Yugoslavia.

Looking back at the related documentation it is impressive to see that the Yugoslav military planners developed and maintained the idea that the JNA should remain capable of continuing to defend the country even after they had been hit by one nuclear weapon. In 1962, they concluded that even the deployment of multiple nuclear weapons against one air base was unlikely to render that air base entirely nonoperational. Underground facilities were seen as a sort of a guarantor that this would be the case.

Unsurprisingly, the resulting concepts prompted them into the decision to construct extensive underground facilities and numerous hardened aircraft shelters (HAS), so as to keep the combat aircraft of the RV i PVO safe even from direct attack by nuclear weapons. If such convictions were not enough, they were only bolstered by the experiences from the June 1967 Arab-Israeli War: this not only exposed the vulnerability of any air force operating from bases that lacked hardened protection facilities, but indeed confirmed the entire concept of the whole-scale people’s defence war: even if large parts of the country were overrun in a conventional war, underground facilities would safeguard the air force’s capability to continue resisting against any kind of aggression.

How Swedish Air Force’s underground facilities Inspired the Construction of Bihac (Zeljava) Underground Yugoslav Air Force Base
The Swedish Air Force’s underground facilities deeply impressed the Yugoslavs who later developed their own underground facilities for the RV i PVO. (Bojan Dimitrijevica and Milan Micevski ’s collection)

Using nature to improve the camouflage of the entrances

Certainly enough, as of the 1960s there were only a few large underground facilities operated by air forces, and even fewer meant to protect aircraft – in Europe or anywhere else – and their owners were not the least eager to show such highly classified installations to the representatives of the Yugoslav government led by President (and Marshal of the JNA) Josip Broz ‘Tito’.

One exception to this rule was the Kingdom of Sweden, a (nominally) neutral country in northern Europe, positioned between NATO-member Norway, neutral Finland, and the USSR. The Swedes allowed the Yugoslavs to examine some of their underground facilities, prompting their visitors into a number of important conclusions about methods of construction, entrance doors with transversal aircraft contours, the distribution and positioning of underground workshops and storage facilities, the practice of towing aircraft into and out of underground installations, and of using nature to improve the camouflage of the entrances.

Swedish underground facilities Inspired the Construction of Bihac (Zeljava) Underground Yugoslav Air Force Base

Sufficient to say: the Swedish underground facilities deeply impressed the Yugoslavs, driving them to the decision to construct something similar of their own. This was how the idea came into being to construct many of the smaller underground facilities present at all of the major Yugoslav air bases. Indeed, the idea for the construction of a major underground air base outside Bihać was also born.

There were a few other underground shelters built at Yugoslavia’s air bases, but Bihać underground air base remained the only underground facility which was permanently used. Nowadays, its ruins are a place of pilgrimage for many aviation and military enthusiasts, and is known as ‘Zeljava’, after a nearby village on the Croatian side.

Tito’s Underground Air Base Bihac (Zeljava) Underground Yugoslav Air Force Base 1964-1992 is published by Helion & Company and is available to order here.

How Swedish Air Force’s underground facilities Inspired the Construction of Bihac (Zeljava) Underground Yugoslav Air Force Base

Photos from open sources


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Dario Leone

Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.
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