Kaliningrad, the Russian militarized exclave surrounded by NATO that triggered Putin’s nuclear threat

Kaliningrad, the militarized Russian exclave wedged between NATO and EU members Poland and Lithuania and a constant flashpoint between the Kremlin and the Atlantic Alliance, has become the center of Vladimir Putin’s nuclear threat against Europeans. Last week Moscow accused NATO of seeking to block Kaliningrad and threatened to use nuclear weapons if the military organization moves forward with that alleged plan. For the Kremlin, the exclave, which gives it a strategic outlet to the Baltic Sea (it is the only port it can use year-round) and is a key node in its hybrid war against Europe, is an advanced bastion. For NATO, it is a piece on the board that shapes any crisis in the Baltic because it could hinder allied military movements.

“We must realize that the moment when nothing can be changed any longer may come very quickly and unexpectedly for everyone,” Russian President Vladimir Putin said last Thursday. Western intelligence services suspect Russia has nuclear weapons hidden in Kaliningrad. Since 2016 it has deployed short-range 9K720 Iskander missiles in the region, which can carry nuclear warheads, and the Federation of American Scientists detected two years later that the Kremlin was modernizing storage facilities for such weapons in the area.

For centuries it was Königsberg, a Prussian city associated with Kant and the Baltic trade routes. After World War II, in 1945, it changed hands, its name, and its population. The German city disappeared and a Soviet city rose on its ruins, which has now become one of Moscow’s key military posts in Europe and at the heart of the EU’s eastern flank. Today its shores host Baltic Fleet facilities and missile and air-defense systems that allow Russia to project power over much of the surrounding sea. In addition, according to Lithuania’s intelligence service, Moscow has been using the exclave as a platform to launch attacks on GPS systems and for electronic warfare against allied countries.

Ruben Stewart, a researcher at the International Institute for Strategic Studies (IISS), explains that the Kremlin has structured Kaliningrad to try to hinder NATO’s entry and movement of forces in the region.

That image of a military “fortress,” however, is not entirely real. Its geographic position is an asset for the Kremlin but also a vulnerability. In a protracted war, keeping a territory surrounded by NATO countries supplied would pose a considerable logistical challenge. There is no Russian land border that allows troops and materiel to be sent directly from the mainland. Access depends on the sea, the air and, in peacetime, on transport links that cross Lithuania.

Since Finland and Sweden joined the Atlantic Alliance (in 2023 and 2024, respectively), the Baltic Sea has effectively become a NATO lake. And since then, the exclave has been more encircled and Russia has stepped up its rhetoric and accusations against Europeans over an alleged isolation of Kaliningrad, a key port for the Kremlin’s external projection.

The Russian fleet deployed there has the mission of “ensuring the safety of navigation” for Russian vessels crossing the Baltic Sea. On one hand, it is an outpost in waters where the Kremlin in recent years has carried out one of its main sabotage operations against Europe: cutting undersea cables. On the other, its destroyers escort older tankers flying third-country flags that Moscow uses to evade sanctions imposed on its hydrocarbons after the invasion of Ukraine.

In recent weeks the situation has heated up. On September 23, a Russian military Mi-8 helicopter originating from the region entered Polish airspace for about 42 seconds, penetrating some 300 meters; Warsaw scrambled fighters to respond to the incident and its military command said Moscow could be testing the reaction capability of Polish air defenses. There have been other incidents with Russian aircraft entering and leaving Kaliningrad without filed flight plans and, in several cases, with their transponders switched off. Between September 21 and 27, NATO air policing recorded six such episodes around the Baltic states.

NATO has reinforced its presence in the area, with more troops in Lithuania, greater emphasis on its air surveillance missions, and protection of critical infrastructure. There have also been new military exercises. The Alliance has denied the Kremlin’s accusations and stressed that it is a defensive organization. On September 30, NATO Secretary General Mark Rutte said that despite Russia’s threats there is no imminent threat to Alliance territory.

The Kremlin says NATO threatens Russia, but paradoxically it has weakened its defenses on its border to replace losses in Ukraine. British intelligence found in 2023 that the Russian armed forces withdrew several of their valuable S-400 air-defense systems from Kaliningrad to deploy them on the Ukrainian front. Likewise, a significant portion of its ground troops perished after being sent to the Kharkiv front, according to documents found at one of the bases they abandoned.

Moscow removed part of the region’s defenses despite the situation in 2022, when Lithuania restricted the transit of sanctioned goods to Kaliningrad through its territory because of the invasion of Ukraine. The Kremlin denounced a supposed NATO “blockade,” although the province did not experience any supply crisis at any time, as this newspaper verified in situ.

“If it comes to a direct attack on the Russian Federation — in this case, we are referring to Kaliningrad, and perhaps other territories as well — the question of the Russian Federation deploying all the weapons at our country’s disposal will, of course, inevitably and immediately be on the agenda,” Putin warned last Thursday. What the Russian president did not clarify was what response Moscow expects from Europe to its escalation of attacks — including assassination attempts, as happened with the president of arms maker Rheinmetall in 2024 — and bomb and drone attacks, such as the one at Leipzig airport this summer.

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