Don't mess with Russia:
https://www.newyorker.com/news/our-columnists/putin-lied-about-his-nuclear-doctrine-and-promised-russians-that-they-would-go-to-heavenwhat makes this portion of Putin’s talk—the portion that made headlines in both state-controlled and independent Russian-language media—particularly bizarre, is that Putin was misrepresenting the Russian nuclear doctrine.
Russia strengthened the language of its military doctrine in December, 2014. The unclassified portion of the document identifies NATO as the source of the primary threat to Russia’s security. On the subject of a nuclear strike, it says the following: “The Russian Federation reserves the right to use nuclear weapons in response to an attack on Russia and/or its allies involving the use of nuclear weapons or other weapons of mass destruction as well as in the case of aggression against the Russian Federation with the use of conventional weapons when the existence of the state itself is threatened. Decisions regarding the use of nuclear weapons are made by the President of the Russian Federation.”
In other words, Russia reserves the right to use nuclear weapons in response to anything it interprets as aggression, whether or not the aggression involves nuclear weapons or even Russia itself. In still plainer words, the Russian military doctrine provides for the possibility of a first nuclear strike, and Putin was lying.