Russian Foreign Ministry spokesperson María Zakharova said European arms factories producing weapons for Ukraine are "potential military targets" for Russia, and that no one should assume plants outside Ukrainian territory producing weapons for the "regime in Kyiv" will be safe — "whoever thinks so is mistaken" [12][15][34]. She framed European governments as directly involved in the conflict through their military support to Kyiv [34][15].

The warning came hours after Moscow sent NATO a diplomatic note — confirmed by NATO spokesperson Allison Hart as a "non-paper" [28] — stating that Russia would be "ready to use the entire arsenal of forces and capabilities at its disposal, including nuclear weapons" should the alliance attempt to isolate the Kaliningrad exclave from the rest of the country, and raising the possibility of strikes on allied decision-making centres "from the outset" [16][13]. NATO replied in writing, calling on Russia to end its "unprovoked full-scale invasion of Ukraine" and to cease its "irresponsible nuclear rhetoric" [16][30].

EU Defence Commissioner Andrius Kubilius said a Russian strike on weapons factories in European territories would trigger the alliance's mutual defense clause. "If Russia will hit our factories in European territories, that would be Article 5," he said [18]. His statement came amid a growing number of suspicious incidents at arms factories across Europe, some attributed to Russia [18].

NATO itself dismissed the Russian messaging. Secretary General Mark Rutte said the alliance's answer was that it is a defensive alliance and that Moscow should "stop the nuclear threat," calling the messaging "absolutely not called for and not helpful" [21][13]; he added that NATO would "defend every inch of NATO territory" [23] and said the alliance faces no "immediate threat" from Russia [20]. Hart said the alliance "strongly denounce[s] the threat of force, including any irresponsible nuclear rhetoric" [28][21]. The European Commission likewise condemned the "irresponsible nuclear rhetoric" and said it would not amplify Moscow's intimidation and alarmism tactics [1]. President Vladimir Putin, speaking at the Valdai forum, insisted Russia was not threatening anyone and would put the use of all its weapons on the agenda only in response to a direct attack [4][29]; Kremlin spokesman Dmitry Peskov described the messages as reminders to "hotheads in Europe" of Russia's doctrinal documents [16][39].

European leaders pointed to attributed incidents as evidence of a Russian hybrid campaign. Germany accused Moscow of orchestrating an attempted drone attack after an explosives-armed drone was found on the tarmac at Leipzig Airport near Ukrainian cargo planes, and Chancellor Friedrich Merz said Germany is preparing for further hybrid attacks, "including serious ones" [15][4]. Estonia said Russian intelligence was behind an August arson attack on a building belonging to an Estonian defense contractor in Tallinn [15][33], and Polish Prime Minister Donald Tusk warned Russia could stage an "accidental" drone incursion into NATO territory to test the alliance's unity [15]. Rutte warned that "Europe is not at peace today" amid the growing list of such attacks [11].

Russian officials, for their part, cast Europe as the warring party. Foreign Minister Sergey Lavrov said that by supplying the weapons Ukraine fires at Russia, Europe is waging war against his country [12], and Deputy Security Council Chairman Dmitry Medvedev accused European leaders of deliberately provoking a confrontation whose risk, he said, is the highest since 1945 [12]. Zakharova's warning landed on a concrete industrial program: Poland's plan to host production of Patriot interceptor missiles, which Medvedev had earlier threatened with missile strikes [12][37].

The EU is preparing an emergency protocol under Article 42.7 for responding to hybrid threats, which High Representative Kaja Kallas said will not duplicate NATO's mechanisms [12]. Vienna-based nuclear analyst and former Russian diplomat Nikolai Sokov warned of a risk of mutual miscalculation over the Baltic, noting that what European capitals would calculate as pressure just below the level of war — such as a blockade of the Baltic Sea — Russia would see as open war [13][44].