Russia has warned the North Atlantic Treaty Organization (NATO) in writing that it is prepared to use nuclear weapons if allies try to isolate Kaliningrad, its militarized enclave between Poland and Lithuania. The Alliance, of which Spain is a member, confirmed receipt of the document this Wednesday and rejected Moscow's accusations of an alleged plan to blockade the territory.
The note states that Russia would resort to "the entire arsenal of forces and capabilities at its disposal, including nuclear weapons" to defend the region. Furthermore, it contemplates attacks against the decision-making centers of allied countries from the beginning of an eventual conflict and accuses NATO of following a course that could lead to a direct armed confrontation.
The document was conveyed through a 'non-paper', an informal diplomatic communication, as explained by the Alliance. Moscow presents military maneuvers and increased surveillance in the Baltic as signs of preparation to blockade Kaliningrad. NATO has responded in writing that its exercises and operations are defensive in nature and do not threaten any part of Russian territory.
Mark Rutte, the organization's Secretary General, demanded this Wednesday that the Kremlin abandon this rhetoric. "We are a defensive alliance. Enough with nuclear threats," he stated at a meeting organized by 'Euronews' in Brussels. Rutte ruled out an imminent threat to allied territory and argued that the response involves maintaining calm, strengthening defense, and continuing to support Ukraine.
Why Kaliningrad matters
Kaliningrad belongs to Russia, but is separated from the rest of its territory and surrounded by two members of the European Union and NATO, Poland and Lithuania, in addition to the Baltic Sea. Its capital was the German city of Königsberg and it became part of the Soviet Union after World War II. The region has about one million inhabitants.
Its military importance far exceeds its size. The port of Baltiysk houses one of the main bases of the Russian Baltic Fleet, and the region hosts air defenses and Iskander missiles capable of carrying nuclear warheads. It is a platform from which Moscow can project force over northern and central Europe, although possessing these systems does not by itself prove that every deployed missile carries a nuclear charge.
The same location that provides it with strategic value also complicates its defense. Supplying or reinforcing Kaliningrad in case of war would be more difficult due to its separation from the main Russian territory. Finland's incorporation into NATO in 2023 and Sweden's in 2024 expanded the allied presence in the Baltic and narrowed Moscow's military room for maneuver in the region.
Another particularly sensitive point is the Suwalki corridor, the border strip between Poland and Lithuania located between Kaliningrad and Belarus, a Russian ally. It is the land connection of Estonia, Latvia, and Lithuania with the rest of NATO territory. An attack that cut off this passage would make it difficult to send reinforcements by land to the three Baltic countries, which explains the attention it receives in allied defense plans.
Moscow also questions operation 'Baltic Sentry', launched in January 2025. NATO created it to protect communication cables and other critical underwater infrastructure after several incidents in the area. The deployment includes frigates, patrol aircraft, and surveillance assets. Spain has participated with the frigate Almirante Juan de Borbón.
Sabotage and military pressure
The nuclear warning comes during a period of increasing tension due to episodes of a different nature. Last Thursday, Finnish and Swedish fighter jets intercepted and identified a group of Russian military aircraft over the Gulf of Finland. The aircraft were flying in international airspace, according to the Finnish Air Force, so that operation should not be confused with a violation of an allied country's airspace.
On Tuesday, the Estonian government attributed to Russian special services the arson attack in August at the facilities of Milrem Robotics, a defense company in Tallinn. Estonian authorities called it sabotage aimed at intimidating and reducing support for Ukraine. Moscow rejected the accusation. The case reflects how the confrontation extends to companies and infrastructure linked to military aid to the invaded country.
The High Representative of the European Union for Foreign Policy, Kaja Kallas, addressed that campaign with community Defense ministers on Monday. The EU considers that the sabotages, fires, and incursions seek to weaken European unity, and is studying reinforcing its response along with coordination with NATO. These actions allow pressure to be exerted on allies without necessarily resorting to an open military offensive.
Since the full-scale invasion of Ukraine in February 2022, the Kremlin has repeatedly used nuclear warnings in the face of increased Western support for Kyiv. In November 2024, Putin expanded the assumptions of his nuclear doctrine to contemplate a response to certain conventional aggressions that represent a critical threat to the sovereignty or territorial integrity of Russia or Belarus. The doctrine reserves this possibility for Moscow and leaves the final decision in the hands of the Russian president, without establishing an automatic nuclear response to any incident.
The Kremlin spokesman, Dmitry Peskov, justified this Wednesday the warning about Kaliningrad as a reminder of those documents. NATO, for its part, has condemned the "irresponsible nuclear rhetoric" and has insisted that the threats will not alter its support for Ukraine or its willingness to defend allied territory.
Russian pressure also reached European industry this Wednesday. Maria Zakharova, spokeswoman for the Russian Foreign Ministry, has indicated that factories located in Europe that produce weapons for Ukraine are potential military targets for Moscow. In response to a question about the possible manufacture of Patriot missiles in Poland, she warned that these facilities should not be considered safe just because they are outside Ukraine. "Whoever thinks so is wrong," she declared.
