On 30 September 2026, Russia notified the North Atlantic Treaty Organization (NATO) that it was ready to use its arsenal of weapons, including nuclear weapons, should the Alliance attempt to isolate the Kaliningrad Region from Russia.[i] The warning came after Polish Foreign Minister Radosław Sikorski proposed on 11 September 2026 that NATO military exercises around Kaliningrad be intensified in order to force Moscow to redeploy some of its military assets away from Ukraine.[ii]
In the same period, Russia has been expanding its military personnel capacity following the first State Duma parliamentary elections held in wartime. On 28 September 2026, President Vladimir Putin signed a decree raising the total personnel strength of the Russian Armed Forces to 2 million 440 thousand, of whom 1 million 550 thousand 500 are on active duty. The decree does not amount to a new partial mobilization similar to the one declared in September 2022. Nevertheless, Russia has also launched its autumn conscription campaign, under which around 120 thousand men are expected to be called up for compulsory military service.[iii] These developments indicate that, in addition to responding to the current pressure around Kaliningrad, Moscow is trying to put in place the means necessary to rebuild its broader military capacity.
Kaliningrad holds a distinctive position in Russia’s military strategy towards Europe. Geographically separated from the Russian mainland, the exclave lies between Poland and Lithuania. Kaliningrad therefore provides Moscow with a forward military deployment option in the Baltic Sea region. The region hosts significant naval, missile, air defence, electronic warfare and other military capabilities that enable Russia to project power in the Baltic Sea and to restrict NATO’s freedom of movement on its north-eastern flank. However, Kaliningrad’s geographical location also creates a strategic dilemma for Moscow. Unlike the regions on the Russian mainland, Kaliningrad cannot be reinforced via a continuous land corridor. In the event of a large-scale conflict, reinforcement of the region would depend on air and sea lines of communication whose security is contested, and no unrestricted land route would be available.
Sikorski’s proposal brought this vulnerability to the centre of the debate. Sikorski argued that NATO should conduct military exercises near Kaliningrad extensive enough to create uncertainty in Moscow and potentially force Russia to withdraw troops from Ukraine and shift them to other areas. Although Sikorski explicitly rejected the idea of seizing the region, his proposal exposed the tension between Russia’s concentration of a significant share of its resources on the war in Ukraine and its need to protect strategically important regions elsewhere.[iv] In this context, Kaliningrad’s vulnerability may give NATO additional leverage to increase military pressure on Moscow at a time when Russia is concentrating a significant share of its military resources on the war in Ukraine.
Russia, for its part, has responded to this conventional challenge through nuclear signalling. Moscow’s diplomatic note of 30 September 2026 described NATO’s approach as dangerous and warned that Russian strikes could be carried out against decision-making centres in NATO member states at the outset of a conflict. More importantly, it stated that Russia was ready to use nuclear weapons to defend the region should NATO try to isolate Kaliningrad. NATO Secretary General Mark Rutte, however, dismissed the warning, stating that there was no imminent threat to NATO territory.[v] The difference between these two positions shows that the current issue concerns deterrence and escalation management rather than the threat of a near-term nuclear conflict. By adding a nuclear dimension to a conventional scenario, Russia may seek to make NATO governments weigh whether applying military pressure around Kaliningrad could lead to an escalation beyond the original purpose of the exercise.
Russia’s resort to such rhetoric also reflects a more complex military reality. The Russian military grouping in Kaliningrad is temporarily weakened, as a significant portion of its ground forces and combat equipment has been sent to the war in Ukraine. Lithuania’s 2026 National Threat Assessment states that there are plans to transform the naval infantry brigade stationed in Kaliningrad into a division and to form additional units in the region. The report also draws attention to ongoing military infrastructure upgrades, including radar and logistics capabilities.[vi] In this context, Kaliningrad should not be regarded as a permanently depleted outpost. A more accurate assessment would treat the region as a strategically important military formation whose conventional capacity has been reduced by the war in Ukraine, but whose long-term restructuring is already under way. Kaliningrad retains its strategic importance for Russia; however, the capacity of the conventional forces currently in the region has been limited by the war in Ukraine. As the importance Russia attaches to the exclave in its broader Baltic strategy grows, so does the cost for Moscow of acknowledging its conventional weakness in the region.
The persistent rumours of a possible new mass mobilization and the decree of 28 September 2026 are important for understanding Russia’s posture. The Russian General Staff is reported to be preparing to mobilize approximately 300,000 personnel each year in 2026 and 2027. In addition to these forces, it is stated that Russia needs to recruit around 400,000 people per year merely to replenish its existing units. As for the presidential decree of 28 September 2026, it does not declare a new mobilization. The decree does not in itself amount to a new partial mobilization. Instead, it raises the authorized personnel ceiling of the Russian Armed Forces and provides for the government to allocate the budgetary resources needed for the broader military structure. This was the fourth increase in the authorized military personnel strength within 2026.[vii] Moscow is also increasingly relying on administrative pressure and on tightening measures introduced in the military registration system to sustain the flow of personnel.
The prospect of a broader mobilization remains strategically significant. In July 2026, Russian military officials were reported to have conducted mobilization readiness exercises in the Kaliningrad Region. Western intelligence officials also noted that similar preparations had been carried out in other regions of Russia and stated that these exercises were designed for a possible future mobilization rather than reflecting a mobilization decision already taken.[viii] The testing of these procedures shows that Moscow is assessing not only its capacity to generate additional manpower, but also how such personnel could be integrated into a strategically vulnerable military region.
In the State Duma elections held in September 2026, the United Russia Party retained its constitutional majority by winning 57.83% of the party-list vote. The election results do not directly prove that the Kremlin took a mobilization decision after the elections; however, they may have removed an important element of the political calendar. Before the elections, a large-scale mobilization could have entailed considerable domestic political costs, since the 2022 experience is still politically sensitive. Following the elections, the Kremlin may have greater room for manoeuvre to intensify recruitment or to implement selective manpower measures without facing a new federal electoral test in the near term.
It would be misleading to assess Russia’s force generation policy solely on the basis of whether the Kremlin issues a formal mobilization decree. Moscow may gradually increase the personnel strength of the Armed Forces while avoiding the political shock that a new nationwide mobilization would cause. Such an approach could include larger conscription campaigns, expanded contract recruitment, increased administrative pressure on potential recruits and preparations for the rapid integration of reserve personnel into the armed forces should circumstances require it. The mobilization exercises reportedly conducted in Kaliningrad suggest that at least some elements of this infrastructure may have been preserved. Therefore, the absence of a formal mobilization order should not be interpreted as an absence of mobilization capacity on Russia’s part.
Russia’s nuclear signalling may be serving as a bridge between its current conventional limitations and its future force structure. At present, Moscow may seek to use nuclear rhetoric to prevent NATO from exploiting Kaliningrad’s temporary weakness. At the same time, the conventional capacity that underpins the region’s strategic importance may be gradually restored through the expansion of military capabilities and manpower generation. Nuclear signalling therefore does not necessarily have to replace conventional military power. On the contrary, it may provide Russia with an additional deterrence advantage while its conventional capacity is being rebuilt.
For Lithuania and NATO, the main danger may not necessarily be an imminent Russian attack. According to NATO’s current assessment, there is no imminent threat to Alliance territory. The more likely risk may be a security dilemma arising from mutual preparations. NATO may step up exercises, surveillance activities, maritime security, air defence and reinforcement planning around the Baltic Sea. Moscow, in turn, may regard these activities as preparations to isolate Kaliningrad and respond with additional deployments or nuclear rhetoric. NATO may then regard these responses as an indicator that Russia’s military posture is deteriorating. In this way, measures taken to reduce vulnerability may heighten the other side’s threat perception. This risk may grow further, particularly if both sides assess each other’s preparations on the basis of worst-case scenarios.
Nevertheless, nuclear signalling may remain an attractive tool for Moscow, since its cost is considerably lower than that of rebuilding conventional military capacity. While Russia can issue a warning within a few days, re-establishing a fully staffed and equipped military formation requires time and infrastructure. This asymmetry gives nuclear rhetoric particular strategic value during periods of military reconstruction. The Kremlin may strengthen its future conventional capacity while trying to deter NATO in the current period. In short, this behaviour can be described as a nuclear shadow cast over conventional deterrence. The more Russia reinforces the link between Kaliningrad and nuclear retaliation, the more politically difficult it may become for NATO to develop conventional measures that Russia could portray as a threat to the exclave’s territorial integrity. Nuclear rhetoric can therefore influence decision-making processes even if no change occurs in Russia’s actual nuclear capabilities.
In conclusion, Russia’s recent nuclear signalling over Kaliningrad should not be regarded merely as another instance of rhetorical escalation. The warning has emerged simultaneously with a broader effort by Russia to expand its military capacity and to preserve the mechanisms that could enable the generation of additional personnel. The decree of 28 September 2026, the autumn conscription campaign and the reported mobilization readiness exercises do not prove that a new nationwide mobilization is imminent. These developments may indicate that Moscow is preparing for a protracted period in which manpower and the rebuilding of military capacity will continue to be core elements of its military strategy. If Russia can rebuild its military capacity in the west while continuing the war in Ukraine, the Kaliningrad exclave could become a stronger and more durable instrument of pressure on NATO. For Europe, the main strategic risk is not an imminent nuclear strike, but rather Moscow attaining a more credible military position on NATO’s north-eastern flank as a result of nuclear signalling.
[i] “Russia sends nuclear warning to NATO as tensions rise in the Baltic”, Reuters, https://www.reuters.com/business/aerospace-defense/russia-issues-nuclear-warning-nato-tensions-rise-baltic-2026-09-30/,(Accessed: 04.10.2026).
[ii] “Polish minister proposes drills near Kaliningrad to draw Russian troops from Ukraine”, DefenseNews, https://www.defensenews.com/global/europe/2026/09/14/polish-minister-proposes-drills-near-kaliningrad-to-draw-russian-troops-from-ukraine/, (Accessed: 04.10.2026).
[iii] “Russia to conscript 120,000 men, again promises they won’t be sent to fight in Ukraine”, The Kyiv Independent, https://kyivindependent.com/russia-to-conscript-120-000-men-again-promises-they-wont-be-sent-to-fight-in-ukraine/, (Accessed: 04.10.2026).
[iv] “Polish minister proposes drills near Kaliningrad to draw Russian troops from Ukraine”, op. cit., (Accessed: 04.10.2026).
[v] “Russia sends nuclear warning to NATO as tensions rise in the Baltic”, op. cit., (Accessed: 04.10.2026).
[vi] “2026 National Threat Assessment”, State Security Department of the Republic of Lithuania & Defence Intelligence and Security Service under the Ministry of National Defence, https://www.vsd.lt/wp-content/uploads/2026/03/2026-GR-ENG-El.pdf, (Accessed: 04.10.2026).
[vii] “Putin Orders Russian Army to Increase Troop Size to 1.55M”, The Moscow Times, (Accessed: 04.10.2026).
[viii] “Russia Tests Readiness for New Round of Military Mobilization”, The Wall Street Journal, https://www.wsj.com/world/russia/russia-tests-readiness-for-new-round-of-military-mobilization-87d61b96, (Accessed: 04.10.2026).
