The Russian Embassy in Ireland said in a statement on Wednesday that Moscow would be ready to use its entire arsenal, including nuclear weapons, to defend Kaliningrad if the North Atlantic Treaty Organization (NATO) tries to isolate the territory, according to the Kyiv Independent.

The embassy said NATO is preparing an air and naval blockade of the region, without providing evidence or identifying the source of the claim. A Russian document sent to the alliance and obtained by Reuters says Moscow would use “its entire arsenal” to defend Kaliningrad, according to G1. NATO confirmed it had received an “informal document” from the Russian Embassy in Belgium with the warning about Kaliningrad, according to RTE.