Russia has warned that it would use all of its military resources, including nuclear weapons, if NATO member countries tried to isolate the Russian region of Kaliningrad. The warning was detailed in a diplomatic message shared by Reuters and The Financial Times on September 30. According to the document, Russia would be prepared to use "the entire arsenal of forces and capabilities at its disposal, including nuclear weapons, to defend its territory" if NATO nations sought to cut Kaliningrad off from the rest of Russia. The Russian embassy in Brussels also shared the content of this message on X, expressing concern about what it called "provocative actions" by NATO near Kaliningrad. The embassy criticized the "unprecedented increase in the military activity of the Alliance along our western borders, which include Kaliningrad." This statement reflects Russia's growing unease over NATO's military presence near its borders. NATO responded by stating that its military exercises and activities do not pose a threat to Russia's territory. The alliance also urged Russia to "end its large-scale and unprovoked invasion of Ukraine" and to "refrain from increasingly reckless behavior towards the Allies." NATO called on Russia to stop making "irresponsible nuclear rhetoric" and to de-escalate tensions. NATO countries have been worried about an increase in hybrid attacks, which they attribute to Russia, and have strengthened their military presence, especially along the alliance's eastern borders. Russia regularly criticizes these military buildups, viewing them as direct threats to its security. NATO Secretary General Mark Rutte, speaking in Brussels on September 30, rejected Russia's nuclear threats, calling them "absolutely not justified and unnecessary."