It comes after Russia updated the official nuclear doctrineRussia’s defence ministry has reported that Ukraine has hit Russia with

Vladimir Putin has approved changes to Russia’s nuclear doctrine, setting out new conditions under which the country would consider using its arsenal. The doctrine now says an attack from a non-nuclear state, if backed by a nuclear power, will be treated as a joint assault on Russia.

President Vladimir Putin has signed a revised nuclear doctrine declaring that a conventional attack on Russia by any nation that is supported by a nuclear power will be considered a joint attack.