The geographical location of Sweden on the map of Europe naturally put it on the front line of the Cold War. With a very long shoreline taking most of the northern border of the narrow waters of the Baltic Sea, since jets made their appearance on the stage of military strategy, this Scandinavian kingdom found itself just minutes away from the Soviet Union (which at that time engulfed also today’s Estonia, Latvia and Lithuania), as well as from Communist-led Poland (see for instance this post) and German Democratic Republic (much covered on this website, see for example here).
Keeping up with a long-established tradition of neutrality, dating from soon after the age of the Napoleonic Wars in the early 19th century, during WWII and, afterwards, with the beginning of the Cold War, Sweden managed to stay out of any major explicit alliance with the Western Nations. During the Cold War, by continuing this non-aggressive policy, Sweden was a relevant contributor to the overall stability in the Northern European region.
Considering the early accession of Norway and Denmark to NATO to the West of this sector, in the momentous years following WWII when the USSR was still ruled by Stalin, who had just aggressively sealed the fate of the newly-conquered dominions in Eastern Europe, the independence of Finland, sharing a long, militarily untenable land border to the East with the Soviet Union, was particularly precarious (see Hanko, in this chapter). While leaning towards the West and being historically adverse to Russia, Sweden carefully avoided entering NATO, while still establishing commercial links notably with the UK and France for military supply. This attitude, and the increased geographical distance between NATO and the USSR, likely helped to dilute tension between the two opposing blocs in the area – which nonetheless peaked at some points in history before the demise of the USSR – thus mitigating the chance of an outbreak of hostilities, despite a massive military presence on both sides.
Concerning the military budget however, the neutral policy of Sweden did not by any means entail renouncing to self-defense. A solid economy with natural resources and a well-established tradition in mechanical industry and warfare supply, Sweden was perfectly conscious of the need to sustain its geopolitical role with a credible military power, such to deter as much as possible an aggressor, and ensure survival in case of an open war, even in the high-technology war scenario developing in the post-WWII years. Spared the devastation brought about by WWII, Sweden’s strategy planners and industry started in earnest developing especially ground and air forces.
The development of the air force and the air defense system was carried out in an integrated fashion, within the STRIL (Stridsledning och Luftbevakning, which might be translated into Combat control and Air surveillance) programs. Updated over the years (notably the first being the embryonic STRIL 40, followed by -50, -60 and -80, corresponding roughly to those decades in the 20th century), this program embodied the need for monitoring and self-defense. Considering in particular threats coming from the air, airspace monitoring and related information gathering/processing were carried out through a purpose-designed network of stations and command centers. Having ascertained the type of threat, the Air Force would deploy a proportional countermeasure, accounting for its plans for self-defense. This could be carrying out an intercept by scrambling aircraft – something which happened regularly for the decades of the Cold War, following violations by the Warsaw Pact forces – or, in case of an open aggression, for example deploying SAMs to down attacking aircraft.
The evolution of the STRIL program over the years reflects the development in the technology of the threats, and of the defense system itself. This passed from being based on optical detection and early jets, brought to an intercept point with purely verbal communication, to several types of radars linked directly to situation rooms, and purpose designed aircraft, which starting from the SAAB J35 Draken in the 1960s could receive data of an aggressor via datalink.
After the end of the Cold War and the collapse of the USSR, changes in the geopolitical scenario meant the partial scale-down of the Armed Forces, yet also the update of the still existing Sweden’s surveillance system based on more modern technology. Notably, Russian scouting operations and temporary violations of the air space of Sweden have continued over the years, thus giving a practical reason for maintaining a minimum level of alert.
As shown in previous chapters on this site (see here, here and here), retracing the fascinating history of the Armed Forces of Sweden through visits to dedicated museums, collections and surviving sites, especially the Cold War decades did leave behind some traces, which are still there to be seen.
In this chapter, two sites with many links to the history of STRIL can be found. One is a perfectly preserved installation, a node in the airspace monitoring network in Åstorp, close to Helsingborg. The other is the exceptional technical collection of the Missile Museum in Arboga, run by former staff of the Armed Forces of Sweden and passionate technicians, and preserving in a lively and rich exhibition countless items retracing the history of military missiles, as well as many aspects of air defense, especially in Sweden over the Cold War years.
Photographs have been taken from both sites during visits in the summer of 2025.
Navigate this post – Click on links to scroll
Sights
STRIL Sector Operation Center (SOC), Åstorp
On the origin of the STRIL system – Brief historical note
The STRIL system, an acronym standing for Stridsledning och Luftbevakning, which might be translated into Combat control and Air surveillance, was first systematized in 1948, following the preliminary program STRIL 40, with its roots in the experience gained and in the technology of WWII. A key component of it was the availability of air surveillance stations, physically built as soft manned tower constructions, where staff of the Optical Air Guard, typically voluntary women, kept the airspace under watch (similar to the Royal Observation Corps in Britain, see this chapter). Before 1948, information from these visual intelligence gathering points traveled to a number of decision centers (Jaktcentral, precursors of the Sector Operation Centers) by wire, where additional staff of the Guard managed to create an overall picture of the situation and threats, and military officers could eventually authorize a reaction, typically scrambling aircraft for an intercept, in case of an airspace violation.
With the quick and dramatic evolution of military technology in the first years of the Cold War, the STRIL 50 system, started in 1948 and fully implemented by the mid-1950s, inherited, developed and structured the existing network. The territory of Sweden was divided in 21 sectors, which were covered by optical information gathering points, in the form of 1’300 Air Surveillance Stations (Luftbevakningsstation, or LS in short), i.e. towers like in the previous system, manned by the same Optical Air Guard, which however was now under the control of the Air Force. Arranged in a hub-and-spokes fashion, these stations reported to Sector Operation Centers (or SOC, Luftförsvars Gruppcentral, or LGC), of which 50 existed over the national territory. Finally, the command and control (C2) centers were 11 so-called Air Operation Centers (Luftförsvarscentral, or LFC), where the military staff could authorize and coordinate a counteraction against a threat.
Radar systems, both range-finding and altitude-finding, were a major technological addition of STRIL 50. Initially imported in the form of light or movable systems with moderate capacity, a constant investment in this technology brought to Sweden premium British (Marconi, Decca), Italian (Selenia) and later US (ITT-Gilfillan) technology. Radar information was a mainstay of the STRIL 60 program, largely integrating usual optical LS towers, thus strongly increasing the coverage and range of the pre-existing monitoring system. The level of automation increased steadily over the 1960s and 1970s, merging range, altitude, speed and direction information of a potential threat, and presenting them on a digital plotter to human controllers, directly in the LFC C2 centers. At the beginning of the 1960s, datalink parameter transmission allowed controllers in the LFC to provide flight data of an aggressor to the cockpit of the J35 Draken, avoiding easily detectable verbal communication, for an increased level of effectiveness.
In this constantly evolving technological scenario, the implementation of the OPUS system allowed to still profit from the pre-existing LS and local LGC centers. Within that system, the human operators where supplied with a threat labeling system, allowing them to digitally communicate data of whatever optically detected air traffic, including position and direction. This was automatically collected and filtered in purpose-implemented electronics within the LGC, visualized on a local plot, and forwarded after filtering to the LFC, thus integrating the automatically-processed radar information available to the C2 centers. Perceived also as a safety layer in case of an attack to the inherently vulnerable radar stations, the Optical Air Guard stayed until after the end of the USSR, finally disbanding in 1994.
A visit of the site
What you see in Åstorp is an original, perfectly preserved Sector Operation Center, i.e. an LGC, which stands as an ideal specimen to understand the structure and technology of this element in the defense network implemented through STRIL.
The Center is in a bunker built underground in the rock (as typical to the early Cold War era, see this chapter), and is accessible via a steep and narrow flight of stairs from an unassuming, deceptive wooden hut. Once to the bottom, the structure is all at the same floor level.
A technical room is accessible besides the entrance, with a power generator and electric cabinets for managing power supply in the bunker. The major components in the system, still working, are made by Hägglunds, a major mechanical brand in Sweden (also making the highly successful Bandvagn 206 tracked trailer vehicle, still in use today).
Then you get access to the main hall of the bunker, with a somewhat informal appearance, dominated by armchairs and low tables, and with a kitchenette in a corner. Everything is original and clearly dating from the Cold War era in terms of style.
From this gathering and relaxation point in the bunker, it is possible to reach immediately four relevant functional rooms. The first, and likely the most distinctive, is the situation room, which is visible also from the hall through a large transparent glass window.
To the far end from the entrance is an elevated console desk, with signal receivers, telephones and keyboards.
The room is basically built around a tactical table, with a map of the area pertaining to the SOC, where the information gathered by the LS reporting to this station could be represented graphically. The table you see is possibly the only reconstructed part of the bunker. Over the years, with the technological developments described above taking place (especially in STRIL 60), this table was updated with some degree of automation in the representation of information. The original piece in place when the bunker was decommissioned was taken away at some point, and a careful reconstruction of an analog table has been employed to give a lively idea of the appearance of the situation room in a time when information was managed manually. Furthermore, a regional map and a situation board are visible close to the entrance.
The location was manned by staff of the Optical Air Guard, traditionally women since the WWII era. These were regimented non-military voluntary staff, whereas the commanding officer of the center was from the military. He usually stayed in a second room reachable from the bunker hall, and overseeing the situation room through a smaller glass window.
In that room, his desk has been preserved in a mint condition, with a typewriter, and even military kits with pens and pencils. Close by is a more recent computer console, with a cryptography device.
A very interesting component of the visit is a number of original manuals and publications scattered around the bunker. Among them are aircraft recognition manuals, reporting the silhouette of known aircraft from all nations, and the corresponding relevant performance. These original manuals offer an interesting cutaway of the air force arsenals on both sides of the Iron Curtain, and their evolution over the years.
Another core technical room reachable from the hall is dedicated to signal gathering and management. The appearance here is mostly from the higher-technology phases of STRIL 60 and the OPUS system. Among the most distinctive features are the cabinets with the electronic boards from the era, which allowed for the management of the data coming from the peripheral station of the network, including for filtering, visualization on the situation table, and forwarding to the LFC.
The original devices once employed by staff on top of the LS towers are on display here – two portable consoles, one for vocal communication, and another special console for allowing the controller to specify data of the observation target, including its course. The original battery pack is still in place, with labeling from the time.
Interestingly, some of the older optical gear is actually from Hitler’s Germany, marked with the Eagle of the Third Reich.
Vocal communication lines allowed inbound traffic, as well as broadcasting capability, which could be directed also to the local population in case of an incoming attack, also employing recorded messages.
The fourth technical room accessible from the hall is was for air pumping and filtering. Despite not intended for survival of a numerous staff over a long time span, the bunker had an air filtering capability, as typical from the WWII and early Cold War era, when the bunker was built. Today, this system helps in keeping the place ventilated and fighting humidity. Manual pumps from the time are in place, as well as original spare parts, from governmental supply.
Finally, a small sleeping room, reportedly seldom employed for the task, can be found with original berths.
Getting there and visiting
The site is not open to the public, and credit for allowing me and a friend of mine on this exceptional visit goes to the current manager of the place, Mr. Anders Sundberg, and to Mr. Erik Mårtensson, retired officer of the Armed Forces of Sweden, who arranged this visit. It is possible to visit the place by prior appointment only. Contact sightraider.com to establish contact with Mr. Sundberg, who speaks English and has a detailed knowledge of this site as well as of the entire defense system of Sweden since its origin. A visit is therefore warmly recommended for a first-hand experience of an original site within the defense network, and for learning about it from its knowledgeable manager.
Missile Museum, Arboga
The Arboga Robotmuseum, mostly dedicated to missiles, engines and air defense systems of Sweden, can be found in the town of Arboga, roughly 90 miles west of Stockholm.
The town has a long tradition in warfare development, an heritage which is still lively represented by the presence of the Armed Forces and of companies operating in the field of intelligence and warfare systems, including a branch of SAAB. Their quarters are to the south of the town, where an old airbase can be found, with a one-of-a-kind bunker in the side of a local hill, dating from the 1940s. Today employed as a warehouse and barely visible from the northern fence of the airport, this bunker-hangar was designed for missile-related study and development, witnessing a significant commitment of the Swedish government towards that field of research, and towards the town Arboga as a strategic location, already back in a time when rocketry was in its infancy.
The museum is geographically close to the city center. Besides being supported by the Government within the official network of museums dedicated to the heritage of the Armed Forces in Sweden, it is run by a dedicated group of enthusiasts, mostly former military staff or knowledgeable technicians, which give an especially lively atmosphere to the place.
The display starts with a collection of items retracing the history of rocketry in Sweden. Curiously enough, a rare original V-1 from Hitler’s Germany dominates the display by the entrance! Similar to other locations in northern Poland and the Danish island of Bornholm (see here), territories geographically north of the Third Reich’s experimental laboratory of Peenemunde (see this chapter), and within range of the V-1 and V-2 early self-piloted flying weapons, were crash-landing places for experimental flights gone out of control. Southern Sweden was no exception. Moreover, the one you can see in Arboga is the only well-preserved V-1 landed in Sweden. The good state of conservation is evident looking at the fuselage and engine casing.
Even the onboard systems are almost perfectly in shape, including the knob to set the target distance covered by the flying bomb (measured approximately, by recording the rotations of the small ram propeller to the front). Also the actuators for the movable tail surfaces can be seen. They were fed from two tanks of compressed air, one of them, sectioned, revealing the fabric-inspired construction.
Most interestingly, the pulse-jet core, with the injection pipes and the radially oriented valve system, is also displayed.
For many nations including Sweden, the analysis of the – for the time – very advanced aeronautical projects of the Third Reich constituted a valuable starting point for their own development programs in the field. The topic is relevant to the museum in Arboga, where many early designs of autonomous flying platforms developed in Sweden are represented. Notably, an early project from the Navy, the RB310 on display, from soon after WWII, was pushed by the the same motor type as the German V-1 (note the distinctive side inlets).
Yet until the late 1950s the pulse-jet concept lived on with the RB315 ‘Agaton’, where the air breathing component of a developed version of a pulse-jet (the SM11, not dissimilar at a glance from the original German design) can be seen emerging on the fuselage.
Still air-breathing yet based on small turbojets, two interesting designs from the same era are on display. One is the compact long-range anti-shipping RB15F, developed for the SAAB AJ37 Viggen, and employed as well with the JAS39 Gripen. The other is the target drone developed by Beechcraft in the US as MQM-107, and in service in Sweden as the RB06. Its own small French-made TRI 60 turbojet can be seen below the the aircraft.
Perhaps the most massive among those on display is the ship-mounted version of the RB08A. This design was operationally employed within the Navy (see here), and later for coastal defense employing land-based batteries. It was pushed by a small turbojet by the French company Turbomeca. This heavy radar-homing anti-shipping missile is displayed with some of its 1960s-fashion internal systems dismounted.
A full array of missiles employed by Sweden’s Armed Forces yet originally designed in NATO Countries is on display, along with a number of prototypes and models originally from Sweden.
A less-known chapter well covered here is that of special under-wing pods. For example, the BOY401 flare dispenser for the Gripen reveals a massive sized and non-trivial construction, when checked from a close distance. Even more complex is the BOX3 pod, originally designed in the 1960s for the SAAB J32 Lansen as a decoy dispenser for detection jamming, with provision for flare and even a nose-mounted radar.
Active jammers are represented for example by the Apparat 27 and the U22 capsule, on display side by side, ahead of the fuselage piece and engine from a SAAB J37 Viggen.
A second area of the museum is dedicated to diverse smaller-scale ground-launcher missiles, as well as drones. For example, the very successful RB53 Bantam and RB56 ground-launched anti-tank missiles are on display, with the corresponding aiming device and computer. The bigger RBS17, the Swedish version of the AGM-114 Hellfire, has been placed side by side with others, allowing for a direct size comparison. It is in service with the coastal defense artillery.
An interesting cutaway is offered for the case of the RBS90 surface-to-air missile, revealing the complexity within the casing of this type of weapon. Nearby are two unmanned flying platforms employed by Sweden’s Armed Forces, the French-imported UAV01 and the lighter Swedish design of the UAV02 with its own control console. Sweden employed a SAM systems for protection of strategic sites, like airbases. Notably, the massive British-design Bloodhound missile was employed (one can be seen outside the museum). A detailed scale reproduction of a a SAM battery cand be found here as well.
Cameras, flash lights, pods employed for PHOTINT/SIGINT, and a radar head from the nose cone of a J37 Viggen attack aircraft are on display as well.
Notably, some of the gentlemen behind this collection were deeply involved in the airspace monitoring and defense activities of Sweden (see also the previous site on this page) during their military careers. Their experience with the STRIL initiatives is a fundamental knowledge base in this respect, and a chat with them is warmly suggested for everybody with an interest in this chapter of warfare history. Some of the radar consoles to be found in the top-level nodes of the air defense network (LFC), where all data from peripheral nodes were assembled to represent the detailed situation of the air space, are on display in the collection. They allow the visitor to retrace the technical evolution of the radar technology for air defence.
Notably, since the arrival of the SAAB J35 Draken, it was possible to send the data of an intruder to the panel of the aircraft via datalink from the console of the radar system (in particular the Decca PS-08 radar, of which four covered the exposed territory of Sweden, was an enabler in getting sufficiently accurate data). The console is on display together with the panel of the Draken. A supersonic single-pilot aircraft with exceptional performance, that aircraft was not easy to pilot with a fully analog cockpit. The addition of information on another aircraft, theoretically very effective for managing an intercept, in an operative scenario required a very high skill and preparation by the pilot, to face a very high workload.
The general amelioration of electronics over the years allowed to develop these systems, in conjunction with the appearance on the scene of the SAAB J37 Viggen and later the JAS39 Gripen, greatly reducing the workload of the pilot by displaying target information on scopes or maps, making them more promptly usable.
A mainstay of the defense system, radar consoles allowed controllers to keep the entire airspace of Sweden under watch. During the Cold War, the range of these systems allowed to scan well south of Berlin and within the USSR. However, the vantage geographical position of Sweden on the boundary of the Eastern Bloc put this Nation at risk of intrusion. For safety, in the mutual mistrust among opponents typical to the Cold War, camera recorders were employed since the 1960s to keep trace of radar blips, also to the aim of proofing intrusions or violations. The special camera arrangement on top of a radar scope is on display as well.
These recordings are now a valuable and interesting trace from the past, witnessing momentous events like the withdrawal of Soviet forces following the 1968 Soviet invasion of Czechoslovakia and the (sad) conclusion of the crisis, large exercises of the Warsaw Pact forces over the Baltic, or little-known, evident intrusions of Soviet aircraft over Swedish territory, and even the overflight by a USAF Lockheed SR-71, at its typical, extremely speed. This incredible material, visible in the museum in the form of a cyclically-running documentary, can be purchased as well after visiting.
A big component of the museum is dedicated to a large and neat collection of aircraft engines. The aircraft design program of Sweden, based on the SAAB designs from the late 1940s until the end of the Cold War, was supported by jet engines modified mostly by Volvo, starting from British or American designs.
The presentation in the museum allows to learn much about the specific features of many of these aircraft engines, by displaying cutouts, technical drawings, as well as components of the ancillary systems and utilities (pumps, generators, etc.). Interestingly, a poster-size reproduction of an old picture portrays the local bunker hangar in Arboga (see above).
An interesting display of cockpit panels from Swedish aircraft allows for an analysis of the evolution of their design. An old flight simulator for training purposes, the ubiquitous US-designed Link Trainer, was apparently employed also in Sweden.
Finally, another exceptional feature of this museum is the availability of two simulators of the SAAB Draken and Viggen! These have been prepared making use of sections of their respective fuselages, notably including the cockpit. They make for an unmissable experience for everybody, especially if you already have some piloting experience – in that case, you may have chance to fly one of these two iconic attack aircraft from the Cold War with incredible realism, for example on an intercept mission versus a Soviet cargo, guided by the expert words of an authentic radar controller!
Getting there and visiting
This one-of-a-kind museum on a very interesting and special topic makes for a must-see destination for everybody with an interest in the Cold War. The exact address of the museum is Glasbruksgatan 1, 73231 Arboga. The location has a large parking ahead of the entrance. The premises taken by the collection, on the ground floor of an old industrial building, are compact and easy to tour. Yet the collection is very rich, and a visit interacting with the group of friendly volunteers (some of them speaking English fluently) running the site might easily take 2 hours or more for an interested subject.
Additionally, an experience on the flight simulator is definitely worth a visit on its own. This can be arranged by prior email or call, and combined with the visit. The professional website, with full information on the museum and exhibits in multiple languages, can be found here.
My own exceptional experience on this site together with a friend of mine, which included memorable flights in both Draken and Gripen simulators, was kindly sponsored and arranged jointly by the Volunteers of the Arboga Robotomuseum, in particular Mr. Antero Timofejeff, and by Mr. Erik Mårtensson, both former officers of Sweden’s Armed Forces. To these gentlemen and to the Volunteers go my personal thanks and congratulations!
