Analysts said that the new clauses in Russia’s doctrine appeared to be specifically aimed at Ukraine and its core Western allies.

Pavel Podvig, a senior researcher at the United Nations Institute for Disarmament Studies, said that the change in tone now poses more of a threat to the West.

“The key change is that it’s the aggression that ‘poses a critical threat to the sovereignty and/or territorial integrity’ instead of ‘puts the very existence of the state in jeopardy,’ he said.

Mobile nuclear bunkers

In Russia, reports on Tuesday said that a plan to install hundreds of mobile nuclear bunkers across the country was being rolled out.

The KUB-M class shelters are designed to protect up to 54 people from “natural disasters, light radiation from a nuclear explosion and radiation”.

Russia has increased its nuclear missile tests over the past couple of years and has threatened to fire nuclear missiles at Britain and other Ukrainian allies.