This paper is part of the CSIS Understanding the Russian Military Today executive education program.
Summary
Changes to Swedish defense policy and spending indicate that the defense of Gotland is a major priority, but how capable is Russia of such an expeditionary operation? This piece suggests four major findings which contribute to the conclusion that it would be militarily possible for Russia to take Gotland, but it would be logistically difficult. First, Russia’s major impediments to expeditionary operations are its limited sealift and airlift capabilities. This limited lift capability means that Russia cannot move forces from Kaliningrad to Gotland at a rate fast enough to attain a favorable attacker-to-defender ratio. Russia can achieve this ratio in a timely manner using airborne forces from the Western Military District near Moscow. However, Swedish air and coastal defenses, along with the ground forces stationed on Gotland, would play a crucial role in slowing Russia’s advance and eroding Russian forces.
Introduction
“Russia, in a crisis or war, might grab the island of Gotland and forward-deploy air-defense systems there in order to close the A2/AD-ring around the Baltic states,” argues the Swedish Defense Research Agency (FOI) in a March 2019 report when describing a notional challenge in Gotland. This type of deployment would significantly increase Russian air defense coverage in the Baltic, allowing for better control of the air and maritime environment and increasing the strength of Russia’s anti-access/area denial (A2/AD) capabilities in the Baltic Sea.
Russia’s relatively successful intervention in Syria since 2015 shows that Russia has some capability to conduct expeditionary military operations. Recent changes to Swedish defense policy show prioritization of the defense of Gotland as a deterrent against a possible Russian attack. The small island of Gotland represents key maritime terrain in the Baltic Sea given its proximity to vital air and sea lanes. Sweden passed a new defense act in 2015 that reallocated forces to defend Gotland, has prioritized improving forces for territorial defense, and reinstated selective conscription in 2017. Political and military tensions have risen between Russia and Sweden since 2013, with close approaches between aircraft over the Baltic Sea, a Russian submarine sighting near Stockholm in 2014, and supposed simulated strikes on Sweden in Russian military exercises in 2013 and 2019. Under these conditions, Sweden made its first major increase in defense spending in 20 years with major acquisitions to defend Gotland. Considering known Russian expeditionary capabilities, is Russia capable of mounting the threat for which Swedish defense policy is preparing?
Using the guideline of a favorable ground troop ratio, this analysis shows that a Russian operation in Gotland is a more logistically difficult landgrab scenario than it appears. Russia’s available forces in Kaliningrad provide enough force for a roughly favorable ratio. However, they have major transportation issues, so Russia would be unable to get most troops to Gotland before Sweden could reinforce the island. In order to change the force ratio, Russia would need to transfer troops from elsewhere and would suffer from a corresponding reduction in the element of surprise, giving Sweden the opportunity to augment its defense. Thus, the logistics of moving Russian forces to Gotland are a key sticking point in Russia’s ability to invade Gotland successfully.
Political and military tensions have risen between Russia and Sweden since 2013, with close approaches between aircraft over the Baltic Sea, a Russian submarine sighting near Stockholm in 2014, and supposed simulated strikes on Sweden in Russian military exercises in 2013 and 2019.
Assumptions for an Expeditionary Coup de Main
A campaign in Sweden would be a much closer expeditionary operation to Russia than Syria, making analysis of such an operation a good test of Russian capability. This piece assesses Russia’s ability to mount a moderate-sized surprise attack—a coup de main—rather than a large campaign, so the scenario could either be considered as part of a larger theater of operations or as “a bolt out of the blue” attack. The analysis focuses on the capabilities of Russia and Sweden alone, without intervention by any other state, as a way to assess Swedish defense capabilities and prospects for a Russian surprise attack.
This analysis makes four assumptions to analyze the campaign under strategic surprise, a major operational requirement for a coup de main. First, Russia and Sweden would have access to ready forces only. For Russia, a timeline to call up forces would risk ruining the surprise. Although Western commentators often worry about follow-on military operations after major Russian exercises, this analysis was not conducted with that rolling start. For Sweden, there would not be enough time to call up reserves or utilize under-ready units once the Russian operation began. Second, to achieve surprise, Russia would not conduct any inter-district transfers since it is clear after Russian movements near Ukraine in 2021 that the international community is highly attuned to force movements and snap exercises. Third, Russia will not allocate any traditional ground forces to this mission. Motor rifle brigades are traditionally associated with Western think tank scenarios in which Russia invades the Baltic States and could reduce the probability of Russia successfully achieving a surprise attack. Finally, given that speed and surprise are the core Russian operational requirements, it is assumed that Sweden will not receive defense assistance from any North Atlantic Treaty Organization (NATO) country or Finland because there would not be time for Sweden to convince these countries to deploy their forces.
How much force would Russia need to invade Gotland successfully? There are many estimates of force sizes required to conduct a successful ground attack. Still, one rule of thumb requires the attacker to outnumber the defender at a ratio of 1.5–2 to 1. Although scholars use this ratio for traditional mechanized warfare with breakthroughs on land, it is a reasonable place to start in assessing Russia’s prospects for success in the ground campaign on Gotland. For “certain success,” Russia should employ a force ratio of 2:1 in deployed ground forces to Gotland. There are important qualitative capability differences to consider when analyzing attack success as well; however, this paper will focus on pure force ratio as an entry point into analysis. In-depth combat modeling and deeper consideration of Swedish contestation to Russian lines of communication using aircraft, air defense, and naval assets are required to assess this campaign fully, but this paper continues under the basic premise that if Russia cannot logistically get enough ground force to Gotland in a timely manner, then Russia cannot seize the territory successfully.
Assessing a Coup de Main with Russian Forces from Kaliningrad with a Focus on Lift
When considering only Russian forces in Kaliningrad and Swedish forces ready to defend Gotland, this force ratio is a little below or a little above the required ratio, at between 1.6:1 and 2.11:1. Based on the assumptions made for strategic surprise, Russia has two ready battalion tactical groups (BTGs) of naval infantry in Kaliningrad, and Sweden has one light mechanized regiment and one Home Guard battalion on Gotland. Each Russian BTG is assumed to be between 700 and 900 soldiers. On the ground in Gotland, Sweden has the 350-troop-strong light mechanized 18th battle group (Gotland Regiment), with several dozen Leopard 2A5 tanks and CV90 infantry fighting vehicles,1 and the approximately 500-soldier-strong 32nd Home Guard Battalion.2
While the Home Guard battalion might be less battle ready than Russian units, Russia is still unlikely to achieve a 2:1 force ratio with forces from Kaliningrad before Sweden can reinforce the island with additional forces. Sweden’s 1st Marine Regiment of 1,200 marines, based approximately 170 km away from Gotland in Berga, may be able to respond quickly enough to change the force ratio in Sweden’s favor.3 The 1st Marine Regiment alone would bring Sweden’s ground forces up to 2,050 soldiers on the island compared to Russia’s 1,400 to 1,800 soldiers. Sweden’s 1st Marine Regiment could reinforce Gotland in as little as nine hours using its fleet of CB-90 assault crafts at a top speed of 30 knots. Based on analysis of Google Earth data, there are as many as 35 CB-90 assault crafts at the docks in Berga out of Sweden’s 100+ CB-90 fleet.4With the ability to carry 18 troops per ship,5 a fleet of 35 CB-90s could carry the 1st Marine Regiment to Gotland over two trips in about nine hours.6 This reinforcement is only possible if Sweden has sufficient time and warning, and the Swedish marines can arrive before the Russian naval infantry have arrived in full.
It is unlikely that Russia will be able to deploy forces from Kaliningrad quickly enough to avoid having to face Swedish reinforcements. Forces from Kaliningrad have the greatest likelihood of achieving surprise because they are less than 300 km from Gotland. Kaliningrad’s 336th Naval Infantry Brigade is a high-readiness, all-volunteer,7 and combat-hardened force with experience in Chechnya, Ukraine, and Syria. However, according to FOI, only two BTGs from the unit are readily available at short notice. Tactical air and rotary assets and a handful of small surface combatants and landing ships could support the naval infantry. However, the speed of these BTGs is uncertain due to constraints on air and sea lift. Ropucha tank landing ships (LSTs) could be used to transport the 336th Naval Infantry Brigade to Gotland. Or, alternatively, due to at least one battalion’s “jump status” and interoperability with the Russian Airborne Forces (VDV), Mi-24 or Mi-8 attack and transport helicopters could move the naval infantry.
Transporting the naval infantry on the four-ship LST fleet may prove challenging for three reasons: the slow speed of the LSTs, Swedish coastal defense, and Swedish air-independent propulsion (AIP) submarines. First, LSTs are a slow form of transport; capable of carrying about 230 troops8 each at a speed of 18 knots, the Ropucha LSTs could transport about one BTG of naval infantry (what would amount to a first wave) from Baltiysk to Visby in about 11 hours. Second, the Ropucha LSTs would be targetable at 70 kilometers from Visby with the Swedish RBS-15 Mk II Coastal Defense System.
It is unlikely that Russia will be able to deploy forces from Kaliningrad quickly enough to avoid having to face Swedish reinforcements.
Third, Sweden’s Gotland-class submarines can target the Ropucha LSTs. Sweden’s 1st Submarine Warfare Flotilla has three Gotland-class submarines and one Södermanland-class submarine, with a second Södermanland-class submarine inactive in “material reserve.”9 According to IHS Janes, Sweden typically uses the Gotland-class submarines to patrol the Baltic and the Kattegat on the west side of Sweden, so it is fair to assume there would be at least one Gotland-class submarine deployed in the Baltic Sea.10 The Ropucha LST does not possess a sonar.11 Even if Russia’s Steregushchiy-class corvettes from the Baltic Fleet, capable of anti-submarine warfare (ASW), escorted the landing ships, neither the Steregushchiy-class’s bow-mounted nor towed sonar is likely to be capable of detecting the quiet Gotland-class submarine.12In U.S. simulations, neither the Ronald Reagan nuclear-powered aircraft carrier nor its ASW-capable escorts could detect a Gotland-class submarine. The Gotland-class carries four anti-ship torpedoes on deployment and could allocate one to each of the four Russian LSTs.
Due to the risk to forces and slow speed of LSTs, Russia is more likely to move naval infantry using helicopters or transport aircraft. There are no large transport aircraft based in Kaliningrad, but the Russian 125th Independent Helicopter Squadron at Donskoye Air Base hosts Mi-24 attack and Mi-8 transport helicopters capable of carrying 8 and 24 fully armed troops, respectively.13 Although it is unclear exactly how many helicopters are at Donskoye Airbase, imagery from Google Earth in late May 2021 shows approximately 35 helicopters currently at the airfield. Some of these helicopters belong to the 396th Independent ASW Squadron and cannot transport naval infantry. If half of the visible helicopters are Mi-24s or Mi-8s, the available airlift can only carry about half of one BTG to Visby in 1.5 hours.14 It would take over four trips total to move a force of 1,800 naval infantrymen. This suggests that the flight time alone to get the full two BTGs to Gotland, without counting refueling and loading time on the ground at Donskoye, would be close to 10 hours.15 By comparison, the Swedish 1st Marine Regiment could arrive in around 9 hours. Sweden would likely have earlier warning of incoming Russian helicopters, but even presuming that Sweden only got warning of the helicopters when they first entered the 470-kilometer detection range of Sweden’s Saab Giraffe 8A AESA 3-D radar, it is possible that Sweden could reinforce Gotland by the time Russia had landed the full two BTGs. Notably, this would require that the Swedish marines be at a very ready posture. Therefore, Russia cannot move the naval infantry by helicopter quickly enough to use their force size advantage before the follow-on Swedish forces arrive.
Widening the Russian Operation to Include the Airborne Forces
The only way for Russia to confidently achieve a desirable force ratio is to use reinforcements from the VDV in the Western Military District, which widens the scope of the Russian operation and potentially reduces the element of surprise. The four VDV bases in the Western Military District are home to 12 ready BTGs (two airborne divisions and one air-assault division). Like the Russian Naval Infantry, the VDV are an elite Russian force with high readiness and 80 percent professional contract soldiers. Military transport aircraft such as the Il-76 and An-124 typically transport the VDV. However, the larger An-124 is a low-density asset with just 9 to 11 airframes in Russia. FOI estimates that only 6 airframes are ready in the Western Military District. The An-124 will likely remain a low-density asset because its maker, the Antonov State Company, is located in Ukraine and cut ties with Russia after the 2014 invasion of Ukraine, meaning Russia cannot order more. In contrast, the Russian-produced Il-76 is more plentiful, with 27 airframes available in the Western Military District out of 36; therefore, this smaller plane serves as the backbone of Russia’s strategic airlift.
Russia only needs to transport about four BTGs of VDV to Visby to achieve the 2:1 force ratio required for success in ground assault, rather than all 12 available BTGs. Given the need for airborne assault to seize the Visby and Bunge airfields on Gotland, either the Russian 98th or 106th Airborne Assault Divisions with paratroopers is appropriate for the mission.16 Russian military analyst Michael Kofman of the Center for Naval Analyses (CNA) argues that the VDV has shown its ability to successfully secure airports and fly in follow-on divisions in combat conditions based on operations in Crimea and Ukraine. Russia could escort this transport mission with 4/4+ generation tactical fighters from the Western Military District at a ratio of about 5:2 compared to Sweden’s available Gripen fighters,17 and could use the Iskander missiles in Kaliningrad to degrade Swedish air defense systems in Gotland.
Transporting four BTGs from the Russian 98th or 106th Airborne Assault Divisions would take about four and a half days. This calculation uses the RAND Corporation’s Russian Ground Force deployment calculator published in 2020 based on Russian force and training data as of 2018. Visby Airfield on Gotland is about 1,500 kilometers from the 98th or 106th Airborne Assault Divisions’ bases near Moscow, which is within the unrefueled range of the Russian Il-76 and An-124. Despite being a civilian airport, Visby Airfield is probably capable of hosting these large Russian military transport aircraft because it has a 2,000-meter runway and typically sees 16 to 20 departures and arrivals per day18 from mostly turboprop civilian planes with wingspans larger than the An-124 or Il-76.19 Capable of carrying 120 and 50 metric tons of cargo, respectively, the ready fleet of An-124s and Il-76s in the Western Military District can carry about 2,070 metric tons of people, weapons, and equipment in one trip to Gotland. Based on the loading time in Russia, the flight time to Gotland, and the unloading time, each trip would take about two days. Given the number of available aircraft; the trips needed to carry the weight of four Russian VDV BTGs; the loading, unloading, and refueling time; and the flight time, it would take about four and a half days to move the four VDV BTGs to Gotland in full. Although this seems like a long time for a rapid reaction force such as the VDV, RAND assumes it takes a full 24 hours to load aircraft at the point of embarkation. Paratroopers would arrive more quickly to secure the airfield. This timeline allows Russia to use its force advantage over Sweden even if Sweden reinforces Gotland with additional forces from the 1st Marine Regiment and even the 31st Light Artillery Battalion. Furthermore, four and a half days is unlikely to allow Sweden to get assistance from other countries because a 2021 FOI report estimates it would take a week for the United States, United Kingdom, Germany, France, Poland, Baltic States, and Nordic countries to have 15 to 28 infantry battalions available. At this rate, Sweden and any military assistance it received would be working to eject Russia from Gotland, rather than fending off the attack.
Conclusion: The Devil Is in the Details
In summary, a significant weakness in Russia’s expeditionary capability is the limited sea and airlift available. Russia’s largest military transport plane is a very low-density asset, although the next-largest size is more plentiful. Russia’s limited landing ship fleet is composed chiefly of smaller and slower ships. Given these speed limitations, Russia is unlikely to be able to make use of its force ratio advantage before Sweden can reinforce Gotland using marines from mainland Sweden. Russia would therefore need to broaden the scope of the operation by bringing in additional VDV forces from the Western Military District. This weakens the element of surprise and increases the logistical challenges placed on the Russian military. Finally, Swedish air and coastal defense would play a crucial role in slowing down the Russian advance to give Sweden time to respond. Russia faces some serious logistical challenges in getting ground forces to Gotland, not to mention additional contestation in the air and sea, so it should not be assumed that Russia can quickly seize Gotland in a landgrab.
This analysis uncovers a set of initial policy implications for Gotland’s defense. First, indication and warning are key for Swedish response. Second, Sweden’s improved defense capabilities are vital. The 1st Marine Regiment and 31st Light Infantry Battalion should be highly ready to deploy and respond to a threat. Swedish ground forces need training, as they could be facing some of Russia’s best-trained forces with the most combat experience. Sweden’s recently acquired MIM-104 Patriot20 could provide additional air defense to Gotland, alongside the MIM-23B Hawk. Finally, Swedish submarines should act as a key force protecting Baltic approaches from the Russian surface naval threat. Sweden’s defense investments have improved its capability, but the Russian military is increasingly capable of close-in expeditionary operations.
Russia faces some serious logistical challenges in getting ground forces to Gotland, not to mention additional contestation in the air and sea, so it should not be assumed that Russia can quickly seize Gotland in a landgrab.
Suzanne Freeman is a political science PhD student in security studies and comparative politics at the Massachusetts Institute of Technology’s Department of Political Science and a member of the Security Studies Program.
This publication was funded by the Russia Strategic Initiative, U.S. European Command in Stuttgart, Germany. Opinions, arguments, viewpoints, and conclusions expressed in this work do not represent those of RSI, U.S. EUCOM, the Department of Defense, or the U.S. government.
This report is produced by the Center for Strategic and International Studies (CSIS), a private, tax- exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).
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